1. Frank can build a model airplane in 3 days, Jo can do it in 2, but Moe can only do it in 5 days. If they work together, they’ll build a model plane in how many days?

2. Suppose Airplane A travels North at 12 mph and Airplane B travels West at 9 mph. How far away will the planes be from each other 20 minutes after they left the same airport?

3. In a sports club with 30 members, 17 play badminton and 19 play tennis and 2 do not play either. How many members play both badminton and tennis?

4. In a class of 78 students 41 are taking French, 22 are taking German and 9 students are taking both French and German. How many students are not enrolled in either course?

5. Helpers are needed to prepare for the party. Each helper can make either 2 large cakes per hour, or 35 small cakes per hour. The kitchen is available for 3 hours and 20 large cakes and 700 small cakes are needed. How many helpers are required?

6. Six years ago Anita was P times as old as Ben was. If Anita is now 17 years old, how old is Ben now in terms of P ?

7. A machine puts c caps on bottles in m minutes. How many hours will it take to put caps on b bottles?

8. Jeff takes 20 minutes to jog around the race course one time, and 25 minutes to jog around a second time. What is his average speed in miles per hour for the whole jog if the course is 3 miles long?

9. Mary is twice as old as Sue. In seven years, Sue will be six years younger than Mary is now. How old will Sue be in six years?

10. Jack drives from the house to the store in 45 minutes. Bob leaves the house 15 minutes after Jack and gets there at the same time. If Jack drives 30 miles per hour, how fast does Bob drive?

11. A class of 25 students took a science test. 10 students had an average (arithmetic mean) score of 80. The other students had an average score of 60. What is the average score of the whole class?

12. If I drive 30 mph for fifty minutes of trip, how fast should I drive for the remaining 30 minutes so my average speed is 40 mph for the whole trip?

13. If Sue scores 90 on her homework assignments, which are worth 30% of the class grade, what is the minimum number of hours she should study for the final? Her final is worth 70% of the class grade. For every ten minutes she studies, her score goes up 1 point.

14. Two thirds of the boys in the class score an 80 on the exam. The girls have an average of 50. There are 60 students in the class, which is made up of half girls and half boys. What must the remaining one third of boys score so the class average is at least 65?

15. David has been stuffing envelopes at a rate of 5 envelopes per minute (epm). He has been working on this for two hours. He is planning to continue this work for another three hours. How many envelopes should he stuff per minute so that his overall rate will be 6 epm?