1. The values, x in a sample of 15 are summarized as follows Σ(x-c) = 72,Σ(x-c)2 = 499.6
where c is a constant. Given that the sample mean is 104.8.
(a) Find the value of constant c.
(b) Find the variance of x.​

12. the amount of money in a bank account decreased by 21.5% over the last year. if the amount of money at the beginning of the year is represented by ‘n', write 3 equivalent expressions to represent the amount of money in the bank account after the decrease?

The number of chocolate chips in an 18-ounce bag of chocolate chip cookies is approximately normally distributed with a mean of 1252 chips and standard deviation 129 chips. (a) what is the probability that a randomly selected bag contains between 1100 and 1500 chocolate chips, inclusive? (b) what is the probability that a randomly selected bag contains fewer than 1125 chocolate chips? (c) what proportion of bags contains more than 1225 chocolate chips? (d) what is the percentile rank of a bag that contains 1425 chocolate chips?

65% of students in your school participate in at least one after school activity. if there are 980 students in you school, how many do not participate in an after school activity?