A pencil costs $x and a notebook cost $4x. I spend $1 000 on pencils and $1 000 on notebooks. a. Write down the number of pencils I get in terms of x?
b. Write down the number of notebooks I get in terms of x?
c. If I get 15 more pencils than notebooks, how much does a pencils costs?

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?