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: 1) The best estimate for the average cost of tuition at a 4-year institution starting in 2020 =$ 31524.31
2) The slope of regression line b=937.97 represents the rate of change of average annual cost of tuition at 4-year institutions (y) from 2003 to 2010(x). Here,average annual cost of tuition at 4-year institutions is dependent on school years .
Step-by-step explanation:
1) For the given situation we need to find linear regression equation Y=a+bX for the given situation.
Let x be the number of years starting with 2003 to 2010.
i.e. n=8
and y be the average annual cost of tuition at 4-year institutions from 2003 to 2010.
With reference to table we get
By using above values find a and b for Y=a+bX, where b is the slope of regression line.
and
∴ To find average cost of tuition at a 4-year institution starting in 2020.(as n becomes 18 for year 2020 if starts from 2003 ⇒X=18)
So, Y= 14640.85 + 937.97×18 = 31524.31
∴The best estimate for the average cost of tuition at a 4-year institution starting in 2020 = $31524.31
The answer to this rests on knowing that there are four properties of multiplication (which your teacher will likely expect you to know...):
These are:
1. commutative
2. associative
3. multiplicative identity
4. distributive
I won't define each of these -- they should be in your notes or textbook. Look them up.
In this case, we are multiplying three terms together -- on the left hand side the parentheses mean to multiply a and b first, then multiply that by 3. On the right hand side, we multiply b times 3 first, and then multiply the product by a.
This would be an example of the associative property of multiplication: when three or more factors are multiplied together, the product is the same regardless of how the factors are grouped.
Hope this helps!
Good luck
5+5 x 8 dodn yes ok ok i agree
It will be 27 mins to 2 hours I think
