Answer:
.022
Step-by-step explanation:
Answer on Khan
Answer: The axis of symmetry is x=3.
Answer:
124.12 pounds
Step-by-step explanation:
42.8 x 2.9
= 124.12
= 124.12 pounds
Reduce each ratio to its minimum expression to find if they are equal.
35:28

10:8

Since both ratios reduce to 5:4, they are equivalent.
Another way to check a:b is equivalent to c:d, is that a*d = b*c
In this case, this will be true if 35 times 8 is equal to 10 times 28:

Since both products are equal, then the ratios are equivalent.
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