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:
Buy the batteries and stereo online:
4.99*2= $9.98 +$90 = $99.98
6.99-5.00 = $1.99
99.98+1.99=$101.97
3Cds in store
7.97*3= $23.85
5% tax = 1.19
10% off = 2.39
$23.85 - $1.19= $22.66
22.66 + 101.97= $124.63
All in store:
12+100+23.85= 135.85 - 6.45 = $129.40
All online:
9.98 + 90 + 26.85= 126.85 +$1.99 = 128.84
<u><em>(CREDIT: Hussain514)</em></u>
Answer: her sales for the month of May is $55000
Step-by-step explanation:
Let x represent her total sales for the month of May.
Each month she receives a 5% commission on all her sales of medical supplies up to $20,000. This means that for her first sales worth $20000, she earns a commission of
5/100 × 20000 = 1000
She also earns 8.5% on her total sales over $20,000. This means that for sales over $20000, she earns
8.5/100(x - 20000) = 0.085x - 1700
Her total commission for May was $3,975. The expression becomes
1000 + 0.085x - 1700 = 3975
0.085x = 3975 + 1700 - 1000
0.085x = 4675
x = 4675/0.085
x = 55000
Answer:
Step-by-step explanation:
as you can see they want you to find the total out of the gallons so the first thing you want to do is get 1,688 and 1,297 and multiply both of them the total is 2189336 so 1,688 x 1,297=289336
3x-132=0
you need to add all like terms first then answer the equation