Mr. Jacob and Ms. Reese estimate that they will take 5 hours and 6 hours respectively to finish grading the same pile of books individually. If they grade the same pile of books together, the estimated time taken is x hours.
(a) (i) What fraction of the pile of books can Mr. Jacob finish grading in 1 hour? (ii) What fraction of the pile of books can Ms. Reese finish grading in 1 hour?
(iii) What fraction of the same pile of books can both of them finish grading in 1 hour if they grade together?
(b) (i) Form an equation in terms of x and solve it.
(ii) Hence, estimate, in hours and minutes, the time taken by Mr. Jacob and Ms. Reese to finish grading the pile of books together.
Answers
Answer:
A large box contains 18 small boxes and each small box contains 25 chocolate bars. How many chocolate bars are in the large box?
Solution
The number of chocolate bars is equal to
18 × 25 = 450.
It takes John 25 minutes to walk to the car park and 45 to drive to work. At what time should he get out of the house in order to get to work at 9:00 a.m.?
Solution
The time it takes John to get to work: time to walk to car park + time to drive
25 + 45 = 70 minutes = 1 hour and 10 minutes
John needs to get out of the house 1 hour and 10 minutes before 9:00 am at
9:00 - 1:10 = 7:50 a.m.
Kim can walk 4 kilometers in one hour. How long does it take Kim to walk 18 kilometers?
Solution
The time it takes Kim to walk 18 kilometers is equal to
18 / 4 = 4.5 hours = 4 hours + 0.5 × 60 minutes
= 4 hours and 30 minutes.