B) 43 because they increase 3
c) 32 because they decrease 7
45 divided by 50= 90%
0.9*16.50=14.85
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:
(
2
x
−
7
)
(
2
x
+
1
)
Step-by-step explanation:
Answer:
<em>x = 437.3 ft</em>
Step-by-step explanation:
<u>Right Triangles</u>
In right triangles, where one of its internal angles measures 90°, the trigonometric ratios are satisfied.
We have completed the figure below with the missing internal angle A that measures A = 90° - 29° = 61° because the lines marked with an arrow are parallel.
Given the internal angle A, we can relate the unknown side of length x with the known side length of 500 ft, the hypotenuse of the triangle. We use the sine ratio:
Solving for x:
Calculating:
x = 437.3 ft
