Problems of the week- August 10 to August 14

Rewards for Problems of the week:

5 points for the correct answer at your level; 10 points for the next level; 20 points each for 2+ levels up. 

Lower Elementary:
Question: Zachary sold books at a yard sale for 15¢ each and toys for $1.00 each. If he sells 6 books and 3 toys, how much money does Zachary make altogether?
 

Upper Elementary:
Question: Eight students are performing songs for their music class recital. Each song is 5 minutes long. If each music student performs 1 song and all 8 students must be done performing by 9:15 PM, then what is the latest time they can start the recital?
 

Middle School:
Question: A 9-foot tree casts a 6-foot shadow. A songbird casts a 2-inch shadow. A squirrel is twice as tall as the songbird. How tall is the squirrel?
 

Algebra and Up:
Question: The profit earned by a cat-sitting company, measured in thousands of dollars, is modeled by the function f(t) = t² – 8t + 16, wherein t is measured in months and t = 1 is January. During which month does the cat-sitting company earn the least amount of money? How much do they earn?
 

Challenge problem to take home. 20 points for the correct answer. 

Can the sum of two prime numbers be a prime number? Explain.