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
X=5 because 4x5=20 and 20-4=16
Answer:
y = 70x + 20
Step-by-step explanation:
Let me know if I am right
Answer:
6.)D 8.)C 9.)C
Step-by-step explanation:
6.)2 3/4 feet is 33 inches. Then devide 156 by 33 then you get 4.7... from this caleb can only make 4 peices of wood.
8.)First make a proportion 0.125/0.75 to x/1. Then devide 1 by 0.75 and use that number to multipy it by 0.125 and get 0.167. Then devide all the answer choices to see that 1/6 = 0.167
9.) 10/18=0.56 and 45/81=0.56 equal proportion
