Let's call our estimate x. It will be the average of n IQ scores. Our average won't usually exactly equal the mean 97. But if we repeated averages over different sets of tests, the mean of our estimate the average would be the same as the mean of a single test,
μ = 97
Variances add, so the standard deviations add in quadrature, like the Pythagorean Theorem in n dimensions. This means the standard deviation of the average x is
σ = 17/√n
We want to be 95% certain
97 - 5 ≤ x ≤ 97 + 5
By the 68-95-99.7 rule, 95% certain means within two standard deviations. That means we're 95% sure that
μ - 2σ ≤ x ≤ μ + 2σ
Comparing to what we want, that's means we have to solve
2σ = 5
2 (17/√n) = 5
√n = 2 (17/5)
n = (34/5)² = 46.24
We better round up.
Answer: We need a sample size of 47 to be 95% certain of being within 5 points of the mean
Answer: the correct answer is A
Step-by-step explanation:
I just took the test
It wouldn't be A or B, but we need to see the other choices
Answer:
Finding the product of 9, 10 and 9 ; 810
Step-by-step explanation:
Given that :
Length = 10 feets
Width = 9 feets
Height = 9 feets
The volume of a rectangular prism is obtained by :
Length * width * height
The volume could be obtained by taking the product of 10, 9 and 9
Hence, the volume of the rectangular prism is :
(10 * 9 * 9) feet³ = 810 feet³
Number of 1 feet³ boxes = 810 feet³ / 1 feet³ = 810
To find the area of a prism, you calculate the area of the cross-section and multiply that number by the length. The cross-section of this prism is a trapezium, and the formula for this is
.
Insert your given numbers to find out the area of this prism's cross-section:
Now, multiply 90 by the length, 10cm, to find out the volume of the prism;
90×10=900cm³
Therefore, your answer id the third option.
