Question

Select the correct answer.

It is 170 miles from Bruce's house to the city where his brother lives. On his last trip to visit his brother, he drove for 2 hours at 55 miles per
hour. Then he came to some very bad road construction. The rest of the trip took 2 hours. How many miles per hour did Bruce drive for the rest
of the trip?
Va

Answer 1

He drove the rest of the trip at 30 miles per hour

Explanation:

The rule of the distance is D = v × t, where

• v is the speed

• t is the time

∵ It is 170 miles from Bruce's house to the city where his brother lives

∴ D = 170 miles

∵ He drove for 2 hours at 55 miles per hour

∴ t1 = 2 hours and v1 = 55 miles/hour

→ By using the rule above find the distance of this part of his trip

∴ D1 = 55 × 2 = 110 miles

∵ The rest of the trip took 2 hours

∴ t2 = 2 hours

∵ D = D1 + D2

→ Substitute the values of D and D1 to find D2

∴ 170 = 110 + D2

→ Subtract 110 from both sides to find D2

∴ 60 = D2

∴ D2 = 170 - 110 = 60 miles

∵ The rest of the trip is 60 miles

∵ It took 2 hours

∵ D2 = v2 × t2

∴ 60 = v2 × 2

→ Divide both sides by 2

∴ 30 = v2

∴ v2 = 30 miles/hour

∴ He drove the rest of the trip at 30 miles per hour