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27) Nationally, the distribution of weapons used in robberies is as shown in the

ID: 3322981 • Letter: 2

Question

27) Nationally, the distribution of weapons used in robberies is as shown in the table. Weaporn Gun Knife Other Strong-arm 0.40 Proportion 0.42 0.09 0.09 The following data represent the weapon of choice in 1652 robberies on school property Gun Knife Other Weapon Proportion Strong-arm 857 329 122 344 Does the distribution of weapon choice in robberies in schools follow the national distribution? Use 0.01 significance level. Please answer: 1. State the null and alternative hypotheses 2. Find the test statistic 3. Find the p-value 4. State a conclusion

Explanation / Answer

Answer:

1).

Ho: p1=0.42,p2=0.09,p3=0.40, p4=0.09

H1: The distribution is different from national distribution.

2).

Goodness of Fit Test

observed

expected

O - E

(O - E)² / E

329

693.840

-364.840

191.843

122

148.680

-26.680

4.788

857

660.800

196.200

58.254

344

148.680

195.320

256.591

Total

1652

1652.000

511.475

511.475

chi-square

3

df

0.0000

p-value

Chi square test statistic = 511.475

3). P=0.0000

4). Ho is rejected.

We conclude that distribution of weapon choice in robberies in schools are different from national distribution.

Goodness of Fit Test

observed

expected

O - E

(O - E)² / E

329

693.840

-364.840

191.843

122

148.680

-26.680

4.788

857

660.800

196.200

58.254

344

148.680

195.320

256.591

Total

1652

1652.000

511.475

511.475

chi-square

3

df

0.0000

p-value

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