People in a public library were polled on how many books they read in the last five years. Preliminary survey results indicate the sample standard deviation is 18.61 books. How many subjects are needed to estimate the mean number of books read by library users in the last five years within four books with 99% confidence

144

Step-by-step explanation:

From information available

Margin of error = 4

S = 18.61

ME = Z-alpha/2 x s/√n

Alpha = 1-0.99

= 0.01

Alpha/2 = 0.01/2

= 0.005

Z-alpha/2 =2.576

Putting into the formula we have

4/1 = 2.576 x 18.61/√n

When we cross multiply

We have

√n = (2.576 x 18.61)/4

√n = 11.98484

n = 11.98484²

n = 143.63

n = 144

144 subjects are needed to do this estimation

stop using this to cheat on home work

step-by-step explanation:

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hey there!

if she's saving for six months, let's divide the total number we need for the trip by six, dividing it into the amount that needs to be saved for each month.

500 ÷ 6 =

she needs to save at least this amount each month, so we should use this symbol: ≥

let x be the amount she saves each month.

your final answer is x ≥

hope this !