Over the past ten years, the town's population doubled in size. the population is currently 12,000. what was the population ten years ago?

If 10 men take 18 days to mow 60 acres of grass, how long will 15 men take to mow 80 acres?

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?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?