Answers
Answer:
Exact surface area = 500+20pi square cm
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Explanation:
A = area of the bottom face = 10*12 = 120B = area of the left face = 7*12 = 84C = area of the right face = 7*12 = 84D = area of the front face = 7*10-0.5*pi*2^2 = 70 - 2piE = area of the back face = 7*10-0.5*pi*2^2 = 70 - 2piF = area of the top face = 2*3*12+0.5*2*pi*2*12 = 72+24piAll areas mentioned are in square cm, which can be abbreviated to cm^2.
Faces A,B,C are straight forward as they are simply rectangles. The remaining 3 other faces are a bit tricky.
Faces D and E involve subtracting off the area of a semicircle of radius 2 from a 7 by 10 rectangle area. The formula pi*r^2 is the area of a full circle, while 0.5*pi*r^2 is the area of a semicircle. From there, I then plugged in r = 2.
The top face is really a combination of 3 different pieces (two flat, one curved in the middle). Each flat part is of area 3*12 = 36, so that doubles to 2*3*12 when accounting for both flat parts. The curved portion will involve the lateral surface area of a cylinder formula which is
LSA = 2*pi*r*h
but since we're only dealing with half the lateral area, we multiply that by 0.5 to get 0.5*2*pi*r*h. From there, I plugged in r = 2 and h = 12.
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In summary we have these six areas for the faces
bottom = 120left = 84right = 84front = 70 - 2piback = 70 - 2pitop = 72 + 24piAdd up those sub areas to get the full surface area of this particular 3D solid.
120+84+84+(70-2pi)+(70-2pi)+(72+24pi)
(120+84+84+70+70+72)+(-2pi-2pi+24pi)
500+20pi
This is the exact surface area in terms of pi. If you want the approximate version of this, then you could replace pi with 3.14 and compute to get 562.8 cm^2
Use more decimal digits in pi to get a more accurate value. If you use your calculators version of pi, then you should get somewhere around 562.831853 cm^2
In this case, I think it's better to stick with the exact surface area (unless your teacher instructs otherwise).
Related Questions
In an extensive study involving thousands of British children, Arden and Plomin (2006) found significantly higher variance in the intelligence scores for males than for females. Following are hypothetical data, similar to the results obtained in the study. Note that the scores are not regular IQ scores but have been standardized so that the entire sample has a mean of M 5 10 and a standard deviation of s 5 2. a. Calculate the mean and the standard deviation for the sample of n 5 8 females and for the sample of n 5 8 males. b. Based on the means and the standard deviations, describe the differences in intelligence scores for males and females.
Answers
Answer:
mean value of female = 10.000
standard deviation of female = 1.604
mean value of male = 10.000
standard deviation of male = 2.449
Step-by-step explanation:
Given:
n=8 females
n=8 males
The objective is to find the mean and deviation and also based on the mean and the standard deviation have to describe the differences in intelligence scores for males and females
Solution:
The mean and the standard deviation are found by using MINITAB
The MINITAB procedure is explained as follows,
Step 1
choosing start > Basic statistics > Display Descriptive Statistics
Step 2
In variables supposed to enter the columns Female and Male
Step 3
Here choosing option statistics and select Mean and standard deviation
Step 4
Finally clicking OK
MINITAB output is as follows,
variable Mean standard deviation
Female 10.000 1.604
Male 10.000 2.449
b)
From the MINITAB output the mean are same for females and males.
Here the standard deviation of females is less than the standard deviation of males. That is the male scores are more variable when compared to female scores.
please help! I cant figure this out!
