It would take the faucet 18 hours to fill the tank because 18/12=1.5. That means it will be 1.5 times slower to fill the tank up with the hose on. 1.5*12=18.
The best prediction for the number of customers is 5450.
To find this value, you just need to plug in 20 for x into the expression. Then, evaluate it using the order of operations.
8(20)^2 + 100(20) + 250
8(400) + 100(20) + 250
3200 + 2000 + 250
5450
Her overall change in her account would be -$525, because she withdrew $75 seven times.
Using the <u>normal distribution and the central limit theorem</u>, it is found that there is a 0.1635 = 16.35% probability of a sample result with 68% or fewer returns prior to the third day.
In a normal distribution with mean
and standard deviation
, the z-score of a measure X is given by:

- It measures how many standard deviations the measure is from the mean.
- After finding the z-score, we look at the z-score table and find the p-value associated with this z-score, which is the percentile of X.
- By the Central Limit Theorem, for a proportion p in a sample of size n, the sampling distribution of sample proportions has mean
and standard error 
In this problem:
- Sample of 500 customers, hence
.
- Amazon believes that the proportion is of 70%, hence

The <u>mean and the standard error</u> are given by:


The probability is the <u>p-value of Z when X = 0.68</u>, hence:

By the Central Limit Theorem



has a p-value of 0.1635.
0.1635 = 16.35% probability of a sample result with 68% or fewer returns prior to the third day.
A similar problem is given at brainly.com/question/25735688