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suppose that the mean outstanding credit card balance for all young couples in the us is 650 usd with a standard deviation of 420 usd. the distribution is highly skewed to the right. suppose now that one random sample of size 200 is selected from the population of young couples. the mean of this sample is 623 usd. based on this information, which of the following is true?

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There is a 1.70% chance that the average outstanding credit balance will exceed $623.

The z-score formula is used to solve problems with normally distributed samples.

The z score of a measure X in a set with mean μ and standard deviation σ is given by:

Z = X-μ / σ

The Z-score indicates how far the measure deviates from the mean. We examine the z-score table after determining the Z-score to determine the p-value associated with this z-score. This p-value represents the likelihood that the value of the measure is less than X or the percentile of X. Subtraction of 1 from the p-value yields the probability that the value of the measure is greater than X.

The Central Limit Theorem states that for a random variable X with mean μ and standard deviation σ, sample means of at least 30 can be approximated to a normal distribution with mean μ and standard deviation σ.

δ = σ / [tex]\sqrt{n}[/tex],

μ = 650.

σ = 420

n = 200

δ = 420 / [tex]\sqrt{200}[/tex]

δ = 29.7

Z = X-μ / σ

By the Central Limit Theorem,

Z = X-μ / δ

Z = 623 - 650/ 29.7

Z = 0.9

Z = 0.9 has a p value of 0.8830

0.9 - 0.8830 = 0.017

There is a 1.70% chance that the average outstanding credit balance will exceed $623.

To learn more about outstanding credit balance, please refer:

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