A man drove 220 km in 3.5h. Part of the trip was at 60 kph and the rest at 65 kph. Find the time spent at the slower speed.
To find the time spent at the slower speed, we first need to determine the distance covered at each speed.
Let's assume the time spent at the slower speed (60 kph) is t, and the time spent at the faster speed (65 kph) is 3.5 - t (since the total time for the trip is 3.5 hours).
The distance covered at 60 kph can be calculated using the formula:
Distance = Speed × Time
So, the distance covered at 60 kph is 60t kilometers.
The distance covered at 65 kph can be calculated as:
Distance = Speed × Time
So, the distance covered at 65 kph is 65(3.5 - t) kilometers.
According to the problem, the total distance covered is 220 kilometers.
Therefore, we can write the equation:
60t + 65(3.5 - t) = 220
Now, let's solve this equation to find the value of t, which represents the time spent at the slower speed.
60t + 65(3.5 - t) = 220
60t + 227.5 - 65t = 220
Combine like terms:
-5t + 227.5 = 220
Subtract 227.5 from both sides:
-5t = 220 - 227.5
-5t = -7.5
Divide by -5:
t = -7.5 / -5
t = 1.5
Therefore, the time spent at the slower speed (60 kph) is 1.5 hours.