Test on a single proportion
A marketing expert for a pasta-making company believes that 40% of pasta lovers prefer lasagna. If 9 out of 20 pasta lovers choose lasagna over other pastas, what can be concluded about the expertís claim? Use a 0.05 level of significance.
(Textbook Ans : P-value = 0.4044 (with a one-tailed test); the claim is not refuted).
Using binomial distribution to get the P-Value, i have n=10,p=0.40, r=9 and so my answer = 2x 0.7553 (looking up the table) = 1.5106.
(while textbook ans is 0.4044)
so where have i gone wrong ?
Re: Test on a single proportion
My solution emiranda:
Ho: p = 0.4
H1: p > 0.4
Since n = 20, not large enough to use normal approximation for z test statistic.
X: No. of pasta lovers choose lasagna
X ~ Bin (20,0.4)
Since x = 9 > 20(0.4) = 8
P = (X>=9) = 1-(X<9)=1-0.5956(from table) = 0.4044(Cool)
Since P > α=0.05, accept Ho.