Question

A particular brand of tires claims that its deluxe tire averages at least 50,000 miles before it needs to be replaced. From past studies of this tire, the standard deviation is known to be 8000. A survey of owners of that tire design is conducted. Of the 26 tires in the survey, the average lifespan was 46,700 miles with a standard deviation of 9800 miles. Do the data support the claim at the 5% level?

Could someone explain how to get the P-value on TI 84 plus?
(it's hypothesis testing)

P-Value = P (z < -2.10)

Answer 1

Ho: Mu >/= 50000

Ha: Mu < 50000 (left tailed test)

Z= (X- mu) / (SD/ sqrt(n))

= (46700 - 50000) / (8000 / sqrt(26))

= -2.1033

Z at 5 % is 1.645

Since p-value (0.017733) < the alpha value (0.05), the Ho will be rejected

No, the data does not support the claim

Left Tailed z-test (on ti 84 calculator)

1) Calculate z_calc (z_test)

2) 2nd DISTR

3) Scroll down to normalcdf(

4) ENTER

5) Now enter: -1000, z_calc i.e -2.10, 0,1)

6) ENTER

7) Output is the P-value