I got this question wrong. My teacher said something about altitude, but I have not a clue how to do it

What is the percent of increase for a population that changed from 438,000 to 561,000

Kathy spent 5/8 of her money on books and another 1/6 of her money on stationeries.what fraction of kathy’s money was left?

Using pert, adam munson was able to determine that the expected project completion time for the construction of a pleasure yacht is 21 months, and the project variance is 4. a) what is the probability that the project will be completed in 17 months? b) what is the probability that the project will be completed in 20 months? c) what is the probability that the project will be completed in 23 months? d) what is the probability that the project will be completed in 25 months? e) what is the due date that yields a 95% chance of completion?