A credit bureau analysis of undergraduate students\' credit records found that t

Question

A credit bureau analysis of undergraduate students' credit records found that the average number of credit cards in an undergraduate's wallet was 4.07. It was also reported that in a random sample of 137 undergraduates, the sample mean number of credit cards that the students said they carried was 2.9. The sample standard deviation was not reported, but for purposes of this exercise, suppose that it was 1.1. Is there convincing evidence that the mean number of credit cards that undergraduates report carrying is less than the credit bureau's figure of 4.07? (Use = 0.05. Use a statistical computer package to calculate the P-value. Round your test statistic to two decimal places and your P-value to three decimal places.) t = - 12.450 Correct: Your answer is correct. P-value =

Explanation / Answer

Set Up Hypothesis
Null, H0: U=4.07
Alternate, H1: U<4.07
Test Statistic
Population Mean(U)=4.07
Given That X(Mean)=2.9
Standard Deviation(S.D)=1.1
Number (n)=137
we use Test Statistic (Z) = x-U/(s.d/Sqrt(n))
Zo=2.9-4.07/(1.1/Sqrt(137)
Zo =-12.4495
| Zo | =12.4495
Critical Value
The Value of |Z | at LOS 0.05% is 1.64
We got |Zo| =12.4495 & | Z | =1.64
Make Decision
Hence Value of | Zo | > | Z | and Here we Reject Ho
P-Value : Left Tail - Ha : ( P < -12.4495 ) = 0
Hence Value of P0.05 > 0, Here we Reject Ho

mean number of credit cards that undergraduates report carrying is
less than the credit bureau's figure of 4.07

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