On your wedding day, you leave for the church 25 minutes before the ceremony is to begin. The church is 11 miles away. On the way, you have to make an unanticipated stop for construction work. As a result, your average speed for the first 15 minutes is only 7 miles per hour. What average speed in miles per hour do you need for the rest of the trip to get to the church in time? Keep two decimal places.

55.50 miles/hour

Explanation:

time for ceremony = 25 minutes

church miles away = 11 miles

distance x

velocity v

time t

x=v*t

first 15 minutes:

x = 7 miles/h * 15 min

1 hour = 60 min

t1 = 15 min

t1 = 1 hour * 15 min/60 min

t1 = 0.25 hour

x = 7 miles/h * 0.25 h

x = 1.75 miles

miles left to church = 11 - 1.75 = 9.25 miles

rest of the trip:

x = v*t

v=x/t

v = 9.25 miles / (25 min-15 min) = 9.25 miles/10 min

t2 = 10 min

t2 = 1 hour * 10 min/60 min

t2 = 1/6 hour

v = 9.25 miles / (1/6) hour=9.25 * 6 miles/hour = 55.50 miles/hour