Answer: z-test for population mean.
Step-by-step explanation:
Given : purchase of a coin-operated laundry. The current owner claims that over the past 5 years, the average daily revenue was $675 with a standard deviation of $75.
So the null hypothesis and alternative hypothesis will be :-
It means the test will be for population mean.
We assume that this is normally distributed.
We know that we use t-test for sample size less than 30 and z-test for sample size greater than 30 .
Since the sample size is 30, so the test use here is z-test for population mean.
(4/3)x = 20
x = 15
The answer is 15
Answer:
Mean = 272.3
sd = 37.7
Step-by-step explanation:
Mean = sum/n
(221+248+251+255+259+263+264+272+291+297+374) ÷ 11
= 2995/11
= 272.2727273
Variance = (sum of x²)/n - mean²
[(221²+248²+251²+255²+259²+263²+264²+272²+291²+297²+374²)/11] - (2740/11)²
= (831067/11) - (2995/11)²
= 1419.107438
sd² = variance
sd = sqrt(1419.107438)
sd = 37.67104243
Answer:
42 pieces
Step-by-step explanation:
you do 378÷9
then you'll get the answer which is 42 pieces