Question

A manager from a certain well known department store found out the money their customers carry into the store is normally distributed with a mean of $258 dollars and a standard deviation of $35. In a sample of 76 Americans who walked into that store find the probability that a random customer will have more than $260 in his or her wallet

Answer 1

Answer:

0.30924

Approximately ≈ 0.3092

Step-by-step explanation:

To solve for this question, we use the formula:

z = (x - μ)/σ

where x is the raw score

μ is the sample mean

σ is the sample standard deviation.

From the question,

x is the raw score = 260

μ is the sample mean = population standard deviation = 258

σ is the sample standard deviation

= σ/√N

N = 76 samples

σ = Population standard deviation

= 35/√76

= 4.0146919966

Hence,

z = (x - μ)/σ

= 260 - 258/ 4.0146919966

= 0.4981702212

Approximately = 0.498

We find the Probability using z score table for normal distribution

P(x = z) = P( x = 260)

= P( z = 0.498)

= 0.69076

The probability that a random customer will have more than $260 in his or her wallet is calculated as:

P(x>Z) = 1 - P( z = 0.498)

P(x>Z) = 1 - 0.69076

P(x>Z) = 0.30924

Approximately ≈ 0.3092