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?

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.

180

Just took the test

i think ur answer is   (3,-1)