Grade 8 - Mathematics 9.16 Problems on Time and Distance - VI

Example:
George walks from his house to office at a speed of 3 miles/hour. and arrives at the office 25 min late, but when he walked at 4 miles/hour, he reached the office 15 min before time. Find the distance between his house and office.

solution:
Let the distance between house and office be x miles.
Time taken when speed is 3 miles/hour = x/3 hours.
Time taken when speed is 4 miles/hour = x/4 hours.
Difference = x/3 - x / 4 = (4x-3x)/12 = x/12 hours.
= x / 12 * 60 = 5x min.
Difference given in the problem = 25 + 15.
= 40 min.
Therefore, 5x = 40
x = 40/5
x = 8 miles.

Directions: Solve the following problems. Also write at least 5 examples of your own.