Answer:
best close estimate distance is 315 miles
Explanation:
given data
speed v1 = 50 miles per hour
speed v2 = 60 miles per hour
time t1 = 4 hr
time t2 = 7 hr
to find out
best estimate for the distance traveled
solution
we know lower end distance
distance = v1 × t1
distance = 50 × 4 = 200 miles
and
upper end distance
distance = v2 × t2
distance = 60 × 7 = 420 miles
so middle value distance is
v = 55 miles per hour and t = 5.5 hours
distance = v × t
distance = 55 × 5.5
distance = 302.5 miles
so best close estimate distance is 315 miles