Answer:
6
Step-by-step explanation:
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: His total rental cost will be $164.75.
Step-by-step explanation:
Since we have given that
Cost of per day = $30
Cost of per mile after the first 100 miles = $0.65
According to question, he was travelling 215 miles in 3 days.
So, it becomes,
Hence, his total rental cost will be $164.75.
Answer:
V≈33.51
Step-by-step explanation:
Solve for volume
V=4/3πr3
=43·π·23≈33.51032
YQ/SQ = JB/DB
YQ/72 = 60/45
YQ = 72*(60/45) = 96
Selection D is appropriate.
