Answer:
A. 20.81 mph
Step-by-step explanation:
x = speed of the boat in still water.
one part of the trip is 10 miles downstream, where the speed of the boat and the speed of the current add together.
and the other part of the trip is the trip back the 10 miles upstream, where the speed of the current works against the speed of the boat :
10/(x + 15) + 10/(x - 15) = 2
10 + 10×(x+15)/(x-15) = 2×(x+15)
10×(x-15) + 10×(x+15) = 2×(x+15)×(x-15)
20x = 2×(x² - 225)
10x = x² - 225
0 = x² - 10x - 225
solution of a quadratic equation
x = (-b ± sqrt(b² - 4ac)) / (2a)
a = 1
b = -10
c = - 225
(10 ± sqrt(100 - 4×1×-225)) / 2 =
= (10 ± sqrt (100 + 900)) / 2 = (10 ± sqrt(1000)) / 2 =
= (10 ± 31.62) / 2
x1 = 41.62 / 2 = 20.81 mph
x2 is negative and did not make any sense.
A person walks away from a pulley pulling a rope slung over it. The rope is being held at a height 10 feet below the pulley. Suppose that the weight at the opposite end of the rope is rising at 4 feet per second. At what rate is the person walking when s/he is 20 feet from being directly under the pulley
The image of this question is missing and so i have attached it.
Answer:
dd/dt = 4.47 ft/s
Step-by-step explanation:
From the image attached, let's denote the following;
d = horizontal distance beneath pulley
h = height of pulley
l = diagonal from the pulley to the head of the person
v = velocity of rope rising
Using pythagoras theorem;
l² = d² + h²
Differentiating with respect to time and considering h = c^(te) gives;
2l(dl/dt) = 2d(dd/dt)
We are given;
d = 20 ft
h = 10 ft
v = 4 ft/s
We know that velocity in this case is change in diagonal distance with time. Thus;
v = dl/dt = 4 ft/s
From earlier, we saw that;
2l(dl/dt) = 2d(dd/dt)
Thus, reducing it gives
(dl/dt)(l/d) = dd/dt
Now, l² = d² + h²
l = √(d² + h²)
Also, v = dl/dt = 4
Thus;
4(√(d² + h²))/d = dd/dt
4(√(20² + 10²))/20 = dd/dt
dd/dt = 4.47 ft/s
Mr. Ellington has a total of 32 students in his class , The ratio of girls to boys is 3:5, how many girls are in Mr . Ellington's class ?
Add the ratio: 3 + 5 = 8
Divide total students by that:
32/8 = 4
The ratio for girls is 3, multiply the 4 by 3:
4 x 3 = 12
There are 12 girls
Answer:
12
Step-by-step explanation:
If the ratio of girls to boys is 3:5, that means that for every 8 total students, 3 would be girls and 5 would be boys. Therefore 3/8 of the students are girls and 5/8 are boys. If 3/8 are girls, then:
[tex]\frac{3}{8}[/tex] of 32
= [tex]\frac{3}{8} * 32[/tex]
[tex]=\frac{3 * 32}{8} \\= \frac{96}{8} \\= 12[/tex]
There are 12 girls.
You order CDs for $14.25 each and the website charges $4.50 for each shipment.
The expression $14.25p + $4.50 represents the cost of p CDs. Find the total cost for
ordering 4 CDs.
Answer:
$61.50
Step-by-step explanation:
14.25(4) + 4.50
= 57.00 + 4.50
= 61.50
need help asap pls !
Answer:
L={∅}
Step-by-step explanation:
7. In which step does a mistake first occur?
8 + 2 + (3 X 3 -2)
Step 1: 8 +2 + (3 x 1)
Step 2: 8 +2 + 3
Step 3: 4 + 3
Step 4: 7
Answer:
17
Step-by-step explanation:
8+2+(3×3-2)=8+2+(9-2)=8+2+7=17
mistake in the first step
firstly we do × and ÷
then + and -
using appropriate properties , find 7/5 × 5/12 − 3/12 × 7/5 − 1/15
Answer:
[tex] \frac{1}{6} [/tex]
Step-by-step explanation:
[tex] \frac{7}{5} \times \frac{5}{12} - \frac{3}{12} \times \frac{7}{5} - \frac{1}{15} = \frac{7}{5} ( \frac{5}{12} - \frac{3}{12} ) - \frac{1}{15} = \frac{7}{5} \times \frac{1}{6} - \frac{1}{15} = \frac{7}{30} - \frac{2}{30} = \frac{5}{30} = \frac{1}{6} [/tex]
DJVJNNSMKAJABJSHSNSB
20) solve:
[tex] {8}^{2} + 2 = [/tex]
21) solve:
[tex]4(2x + 5y = [/tex]
22) simplify the expression
[tex]4( {2}^{2} + 30) - 4 = [/tex]
Rhombus LMNO is shown with its diagonals.
Rhombus L M N O is shown. Diagonals are drawn from point L to point N and from point M to point O and intersect at point P. All sides are congruent.
Angle MNO measures 112°. What is the measure of angle LMN?
Answer:
hope this help
Step-by-step explanation:
Answer:
90
51
10
Step-by-step explanation:
What is (0,6] n (6,8]?
Answer:
(6) the letter n : intersection which means the number you will find at the first bracket and has the same number at the other bracket
Help anyone can help me do the question,I will mark brainlest.
Answer:
a) 30
b)600pi
Step-by-step explanation:
For the first questions, since the arc is 240°, the area of the sector and circumference will be 240/360 or 2/3 of the total of the circles'. Therefore 125.6 x 3/2 is the circumference, which is 188.4. When we divide this by 6.28, we get 30
Now, since the area is pi r^2 where we know that r=30, we get 900pi as the area of the whole thing, however since the sector is 2/3 of the whole circle, 2/3 x 900pi = 600pi
Match the answers……………..
9 in 8956 = 900
9 in 95675 = 90000
9 = 9 in 124569
9 in 68795 = 90
90000 = 9 in 2549652.........
hope it helps...
6. Alex and Brian park their bikes side-by-side. Alex leaves to visit friends, and Brian leaves 30 minutes later,
headed for the same destination. Alex pedals 5 miles per hour slower than Brian. After 1 hour, Brian passes Alex. At
what speed are they each pedaling?
Answer:
See below.
Step-by-step explanation:
When Brian passes Alex they both have travelled the same distance.
Call this distance d.
Let the speed that Brian passes = x miles/hour.
Distance = speed * time so:
For Alex:
d = (x - 5) * 1.5 ( Alex cycles for 1 + 30 minutes = 1.5 hours)
For Brian:
d = x * 1
So substituting d = x in Alex's equation:
x = 1.5(x - 5)
x = 1.5x - 7.5
7.5 = 0.5x
7/5 / 0.5 = x
15 = x.
ANSWER:
Brian's speed is 15 miles/hour.
Alex's speed is 15 - 5 = 10 miles/hour.
Triangle ABC is a right triangle.
Triangle A B C. Angle A is x degrees, B is 90 degrees, C is (x minus 10) degrees. The exterior angle to angle C is (2 x + 40) degrees.
Which equations can be used to find the value of x? Check all that apply.
x + 90 + (x minus 10) = 180
x + 90 + (2 x + 40) = 180
2 x + 80 = 180
x + 90 = 2 x + 40
(x minus 10) + 90 = 2 x + 40
Answer:
x + 90 + (x minus 10)= 180° can be used to find the value of x.
Answer:
A) X+90+ (x-10) - 180
C) 2x+80 = 180
D) x+90 = 2x+40
Step-by-step explanation:
Good Afternoon I am really stuck on this question whoever solves it I will give them brainliest with no unacceptable question thank you so much!
Answer:
Card picked=2
P(factors of 28)={1,2,4,7,14,28}
total cards=4
in percentage=4 x 20 + 20
80+20=100
Therefore 2 in percentage will be
2 x 20 + 20
=40+20=60%
Guys please help me solve this I’m struggling
Answer:
[tex]Max\ z = 1[/tex]
[tex]Min\ z = -9[/tex]
Step-by-step explanation:
Given
[tex]z = 4x + 5y[/tex]
[tex]x \ge -1[/tex]
[tex]y \le 2x +3[/tex]
[tex]y \le -1[/tex]
Required
The maximum and minimum of z
To do this, we make use of the graphical method
See attachment for graphs of
[tex]x \ge -1[/tex]
[tex]y \le 2x +3[/tex]
[tex]y \le -1[/tex]
The corner points of the function are:
[tex](x,y) = (-1,1)[/tex]
[tex](x,y) = (-1,0)[/tex]
[tex](x,y) = (-1,-1)[/tex]
We have:
[tex]z = 4x + 5y[/tex]
Calculate z with the above values
[tex]z = 4(-1) + 5(1) = 1[/tex]
[tex]z = 4(-1) + 5(0) = -4[/tex]
[tex]z = 4(-1) + 5(-1) = -9[/tex]
So, we have:
[tex]Max\ z = 1[/tex]
[tex]Min\ z = -9[/tex]
Pls help me ! L need help here
Answer:
H. 40 inches
Step-by-step explanation:
On Wednesday, he is 40 inches taller. ... That would make 5 days of growth, for 100 inches. But this is only 3 days therefore he would grow 40 inches taller
Whats 782,835 divided by 5?
Answer:
156,567
Step-by-step explanation:
782,835 ÷ 5 = 156,567
Answer:
it is 165,567
Step-by-step explanation:
u divide
A plank 6m long leans against a vertical wall so that the foot of the plank is 4m away from the wall. A lizard climbs 2m up the plank. Calculate the horizontal distance between the lizard and the wall.
Answer: [tex]\dfrac{8}{3}\ m[/tex]
Step-by-step explanation:
Given
Length of the plank is [tex]6\ m[/tex]
Foot of the flank is [tex]4\ m[/tex] away from the wall
Lizard climbs 2 m up the wall
from the figure, the two triangles are similar
[tex]\therefore \dfrac{2}{6}=\dfrac{x}{4}\\\\\Rightarrow x=4\times \dfrac{2}{6}\\\\\Rightarrow x=\dfrac{4}{3}\ m[/tex]
So, the distance from the wall is
[tex]\Rightarrow 4-x\\\\\Rightarrow 4-\dfrac{4}{3}\\\\\Rightarrow \dfrac{8}{3}\ m[/tex]
#What is the value of the discriminant for the quadratic equation –3 = –x2 + 2x?
Discriminant = b2 – 4ac
–8
4
8
16
Answer:
16
Step-by-step explanation:
the quadratic equation –3 = –x2 + 2x can be changed into :
x²-2x-3= 0
a=1, b= -2 , and c = -3
so, the discriminant = (-2)²-4(1)(-3)
= 4 + 12 = 16
Prove that angle ABD is congruent to angle CBE
with solution!
ANSWER:
the conditions are the angle a is equal to angle c and ab = bc . Hence we need to prove that the triangles is congruent to the triangle cbe. ... angle A =angle C and AB=BC.
There is 10% salt solution and a 30% salt solution. How much of each is needed to make 10L mixture that is 25% salt solution?
Answer:
2.5L of 10% salt solution and 7.5L of the 30% salt solution
Step-by-step explanation:
let the amount of L in the 10% solution be 'x'
let the amount of L in the 30% solution be '10-x'
* because they add up to a total of 10L
10%(x) + 30%(10-x) = 25%(10)
0.1x + 3 - 0.3x = 2.5
-0.2x = -0.5
x = 2.5
x =2.5
10-x = 7.5
2.5 of 10% solution and 7.5% of 30% solution
Value of the boat after 3 years?
after each year it's 83% of it's value from last year (100%-17%=83%)
the function in 19000 * (0.83) ^x
3 will be filled in for x
19000 * (0.83) ^3= 10863.953
$10863.95
Answer:
$10,863.95
Step-by-step explanation:
y = 19,000[tex](.83)^{t}[/tex]
y = 19,000[tex](.83)^{3}[/tex]
y =$10,863.95
PLZZZZ HELPPPPPP!!!!!!!!!!!
Answer:
5/8 boxes
Step-by-step explanation:
1/3 ⋅ 1 7/8 = ?
1/3 ⋅ 15/8 = 15/24
15/24 = 5/8
5/8 boxes
What is the volume?
9 ft
4 ft
2 ft
HELPPPP
Answer:
72?
Step-by-step explanation:
V=whl=4 x 2 x9=72
Please help me fast
Answer:
864
Step-by-step explanation:
A=6a^2=6·12^2=864
Answer:
864 in^2
Step-by-step explanation:
2(144+144+144) = 2(432) = 864 in^2.
Hope this helped!
The tens digits of a certain two-digit number is 1/3 of the units digit. When the digits are reversed, the new number exceed twice the original number by 2 more than the sum of the digits. Find the original number.
Answer:
The orginal number is 26.
Step-by-step explanation:
So the units digit can be 3 6 or 9
The tens digit can be 1 2 or 3
So the original number can be 13
31 = 2*13+ (1+3) + 2
31 =? 26 + 4 + 2
This doesn't work. The right side is 32
26
62 = 2*26 + 8 + 2
62 = 52 + 8 + 2
This is your answer.
3 and 9 won't work because 39 is odd and so is 93. The result has to be even.
A game involves correctly choosing the 5 correct numbers from 1 through 18 that are randomly drawn. What is the probability that a person wins the game, if they enter a) once? b) 7 times with a different choice each time?
Answer:
[tex]=\frac{1}{8568}\ = .00011\\\ =\frac{7}{8568} = .00081[/tex]
Step-by-step explanation:
[tex]5/18\cdot \:4/17\cdot \:3/16\cdot \:2/15\cdot \:1/14=\frac{1}{8568}[/tex]
Independent Practice
Find the first, fourth, and eighth terms of the sequence.
an=0.5 · 3n−1a subscript n baseline equals 0.5 times 3 superscript n minus 1 baseline
A.
0.667; 4.5; 364.5
B.
3; 0.375; 0.0234375
C.
0.5; 13.5; 1093.5
D.
0.5; 121.5; 280.5
Answer:
C.
0.5; 13.5; 1093.5
Step-by-step explanation:
Answer in Detail !!! ✨
Answer:
3300cm²
Step-by-step explanation:
30cm+30cm=60cm 60cm is the lengh of the whole joint structure.We will put it in the equation as "a".
heigh stays the same(10cm) because the pieces are not stacked one on top of the other.They are joined on their sides.We will put it as "c".
Widht also stays the same.its 15 cm and we will put it as letter "b".
So
a=60cm
b=15cm
c=10cm
We need to calculate the surface area of the entire joint structure.
1.First thing to do is to calculate the top part which is:
a*b=15*60=900cm²
2.The bootom side is the same 900cm².
3.The front side is:
a*c=60*10=600cm²
4.The back side is the same as front so it is 600cm².
5.The left side is:
c*b=10*15=150cm²
6.The right side is the same as the left and it is 150cm²
Now we just add it up.
S(surface)=900*2+600*2+150*2=3300cm²
If you want the whole exercise in one equation:
S=2*(a*b)+2*(a*c)+2*(b*c)
