Answer to Question #29009 in Statistics and Probability for precous moyo

Question

one hundred students(100) seat for a mathematical examination. it has been established that the scores from this examination are normally distributed with a mean of 65% and a standard deviation (a=10). what is the probability that students score:
a)less than 75%
b)at least 85%
c)between 60% and 75%.

question 2
a sample of 35 workers was randomly selected from a workforce of 110 to estimate the average amount spent weekly at a canteen by each worker. the sample mean was $13.00 and the sample standard deviation was $3.25
a) calculate a 95% confidence interval for the mean.
b) the canteen owner argues that the average amount spent by each worker per week is $10.00 , test at 5% significance level the claim of the canteen owner.