Answer:
There is no difference in the mean number of times men and women send a Twitter message in a day
Zmen = 0.4
Zwomen = 0.2
Step-by-step explanation:
Null hypothesis: There is no difference in the mean number of times men and women send a Twitter message in a day
Alternate hypothesis: There is a difference in the mean number of times men and women send a Twitter message in a day
Z = (sample mean - population mean)/(sd ÷ √n)
Zmen = (25 - 23)/(5÷√1) = 2/5 = 0.4
Zwomen = (30 - 28)/(10÷√1) =2/10= 0.2
For a two tailed test, at 0.01 significance level, the critical value is 2.576
0.2 and 0.4 falls within the region bounded by -2.576 and 2.576, so we fail to reject the null hypothesis
There is no difference in the mean number of times men and women send a Twitter message in a day
