A recent study done by the National Retail Federation found that 2019 back-to-school spending for all US households who have school-aged children follows a Normal distribution with mean $697 and a standard deviation $120.
Use this information to answer the following questions.
(a) What is the probability that 2019 back-to-school spending for a US household with school-aged children is greater than $893?
(b) Provide the z-score corresponding to the 2019 back-to-school spending of $893.
(c) Based on your answer in (b), what is the probability of 2019 back-to-school spending for a US household with school-aged children is greater than $893?

a) P(x > 893) = 0.051

b) $893 has a z-score of 1.633

c) P(z > 1.633) = 0.051

Step-by-step explanation:

This is a normal distribution problem

μ = mean = $697

σ = standard deviation = $120

We first normalize the $893

The standardized score for any value is the value minus the mean then divided by the standard deviation.

z = (x - μ)/σ = (893 - 697)/120 = 1.633

To determine the probability of 2019 back-to-school spending for a US household with school-aged children is greater than $893 = P(x > 893) = P(z > 1.633)

We'll use data from the normal probability table for these probabilities

P(x > 893) = P(z > 1.633) = 1 - P(z ≤ 1.633) = 1 - 0.949 = 0.051

answer: i think it's a

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.