Question

In: Statistics and Probability

An advertising agency is trying to predict the percent of people who want certain colors of...

An advertising agency is trying to predict the percent of people who want certain colors of nerds. They are claiming that 35% of the people like blue nerds, 45% would like red nerds and 20% would like mixed nerds. A random sample of 500 people revealed that 250 wanted blue, 200 wanted red, and 50 wanted mixed. Does this data suggest that the percentages on which the staffing is correct? Use a level of significance of .05 to test the claim.

Solutions

Expert Solution

null hypothesis:Ho: Sample distribution of colors is similar to as stated by agency .

Alternate hypothesis:Ha: Sample distribution of colors is different then as stated by agency .

degree of freedom =categories-1= 2
for 2 df and 0.05 level of signifcance critical region       χ2= 5.991

Applying chi square goodness of fit test:

           relative observed Expected residual Chi square
category frequency Oi Ei=total*p R2i=(Oi-Ei)/√Ei R2i=(Oi-Ei)2/Ei
Blue 0.35 250 175.00 5.67 32.143
red 0.45 200 225.00 -1.67 2.778
Mixed 0.20 50 100.00 -5.00 25.000
total 1.000 500 500 59.921

as test statistic X2 =59.921 is in critical region we reject null hypothesis

we have sufficient evidence at 0.05 level to conclude that Sample distribution of colors is different then as stated by agency .


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