Answer:
55mph
None of the option is correct
Step-by-step explanation:
Let v be the speed and t as the time taken. If speed varies inversely as the time it takes to drive, then v ∝ 1/t.
v = k/t where k is the constant of proportionality.
IF it takes Kris 5 hours when driving at 55 mph, then v = 55mph when t = 5 hours.
Substituting this values into the formula above;
55 = k/5
k = 55*5
k = 275mp/hr²
To calculate the speed it will Martin to drive for 5 hours, we will substitute k = 275 and t = 5 into the original equation v = k/t
v = 275/5
v = 55 mph
Hence, martin will also need to drive at 55mph to take 5 hours
