In: Statistics and Probability
| 3. At Phil & Jims steak Shop in Parkside [best cheese steak on the planet] they sell about 750 cheese steak sandwiches per day. | |||||||||
| They expect that the mix of sandwiches will be 360 with fried onions only, 165 pizza steask, 120 mushroom steaks & 105 with no cheese. | |||||||||
| Last Wednesday they sold 370 with fried onions, 175 pizza steaks, 110 mushroom steaks & 95 with no cheese. | |||||||||
| At a 95% level of confidence, did their observations fit with their expectations? | |||||||||
| Ho: | fofits fe (observed frequencies are consistent with those expected) | ||||||||
| H1: | fo doe not fit fe (observed frequencies are not consistent with those expected) | ||||||||
| χ2 = | |||||||||
| χ2.05, 3 = | |||||||||
| Ho is | accepted/rejected | ||||||||
| Conclusion: | |||||||||
The null and alternative hypothesis is given as:
f0 fits fe , i.e., the observed
frequencies(f0) are consistent with those of expected
frequencies(fe).
f0 does not fits fe , i.e, the observed
frequencies(f0) are not consistent with those of
expected frequencies(fe).
Observed and Expected frequencies are given in the question as:
| fried onions | pizza steaks | mushroom steaks | No chesse | Total | |
| Observed frequency | 360 | 165 | 120 | 105 | 750 | 
| Expected frequency | 370 | 175 | 110 | 95 | 750 | 
The formula for the test-statistic
is:      
 with degrees of freedom, df=k-1


The test-statistic is calculated as 
Now in the question the confidence level is given as 95% which
means the significance level is 
The critical value with 
 is: 
Since, 
Conclusion:
Since the test-statistic is less than the critical value, which
means we fail to reject(FTR) null hypothesis
H0 . In other words, at 
, the
data does not provide enough evidence to support alternative
hypothesis 
. So we conclude
that the observed and expected frequencies for the sandwiches per
day are not different.