Question

When testing gas pumps for​ accuracy, fuel-quality enforcement specialists tested pumps and found that of them were not pumping accurately​ (within 3.3 oz when 5 gal is​ pumped), and pumps were accurate. Use a 0.01 significance level to test the claim of an industry representative that less than​ 20% of the pumps are inaccurate. Use the​ P-value method and use the normal distribution as an approximation to the binomial distribution. Identify the null hypothesis and alternative hypothesis. A. ​: p0.2 ​: p0.2 B. ​: p0.2 ​: p0.2 C. ​: p0.2 ​: p0.2 D. ​: p0.2 ​: p0.2 E. ​: p0.2 ​: p0.2 F. ​: p0.2 ​: p0.2 The test statistic is z nothing. ​(Round to four decimal places as​ needed.) The​ P-value is nothing. ​(Round to four decimal places as​ needed.) Because the​ P-value is ▼ greater than less than the significance​ level, ▼ fail to reject reject the null hypothesis. There is ▼ insufficient sufficient evidence support the claim that less than​ 20% of the pumps are inaccurate.

Answer 1

Complete question :

When testing gas pumps for​ accuracy, fuel-quality enforcement specialists tested pumps and found that 1294 of them were not pumping accurately​ (within 3.3 oz when 5 gal is​ pumped), and 5705 pumps were accurate. Use a 0.01 significance level to test the claim of an industry representative that less than​ 20% of the pumps are inaccurate. Use the​ P-value method and use the normal distribution as an approximation to the binomial distribution.

Answer:

H0​: p=0.2

H1​: p<0.2 ;

- 3.16 ;

0.0008 ;

p value is < α ; We reject the Null.

Therefore we conclude that there is sufficient evidence to support the claim that less than 20% of the pumps are inaccurate

Explanation:

The null hypothesis ; H0 : p = 20%

Alternative ; H1 : p < 20%

Sample size, n = 1294 + 5705 = 6999

p = inaccurate / total

p = 1294 / 6999 = 0.1849

The test statistic (Z) :

(P - P0) ÷ sqrt((P0(1 - P0)) /n)

P0 = 0.2

(0.1849 - 0.2) ÷ sqrt((0.2 * 0.8)/6999))

−0.0151 ÷ 0.0047812

= - 3.1582029

= - 3.16

Pvalue : using the Pvalue from Zstatistic calculator at α = 0.01

P value = 0.000789

P value = 0.0008 (4 decimal places).

Since p value is < α ; We reject the Null.

Therefore we conclude that there is sufficient evidence to support the claim that less than 20% of the pumps are inaccurate