SOLUTION: You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximate

Question 1197540: You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately
σ
=
21.8
dollars. You would like to be 98% confident that your estimate is within 2 dollar(s) of average spending on the birthday parties. How many moms do you have to sample? Do not round mid-calculation.
n =

Try this with your statistics calculator, if you increases the confidence level, the sample size
decreases
increases

If you increases the error bound, the sample size
increases
decreases
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!


Hi  
 98% confident  ⇒  z = 2.326 (See below)
σ = $21.8,   ME = 2
How large of a sample size is required? 
ME large relative to  σ  ... Expect Sample size to be small

0r
n = 
n =  = 12.7  0r sample Size = 13 (always round Up)

 = CI	z = value
90%	z =1.645  
92%	z = 1.751
95%	z = 1.96   
98%	z = 2.326   Invnorm(.99)  2-sided (.98 + .02/2 = .99 ) 
99%	z = 2.576
Wish You the Best in your Studies.

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