Question

A factory produces bags of rubber bands. A bag of rubber bands has five different sizes: extra large (XL), large (L), medium (M), small (S), and extra small (XS). A quality control specialist collects a random sample of 450 rubber bands from the bagging machine and calculates a chi-square goodness-of-fit test to see if the frequencies for each size in the sample match the hypothesized distribution. The quality control specialist will test his sample against the following null hypothesis.H0:pXL=0.10,pL=0.20,pM=0.40,pS=0.20,pXS=0.10 How many medium rubber bands are expected in the random sample of 450 rubber bands?

Answer 1

Answer:

180

Just took the test

Answer 2

Answer:

The expected frequency is 90

Step-by-step explanation:

If the given probabilities are taken as observed

pXL=0.10,      450*0.1= 45

pL=0.20,      450*0.2= 90

pM=0.40,     450*0.4= 180

pS=0.20,     450*0.2= 90

pXS=0.10     450*0.1= 45

We can assign the expected frequencies to be 450/5= 90 each

The chi square goodness fit test can be calculated as

Observed    Expected   (o-e)       (o-e)²          (o-e)² /e

45                   90         -45            2025              22.5

90                  90           0                0                    0

180                 90           90             8100               90

90                 90            0              0                         0

45                  90         -45             2025                   22.5    

∑                                                                                135        

χ²= 135

The χ² value at 0.05 is 9.49

The result is significant.