What type of weather modification involves the use of large fans to mix surface air with air aloft?

The type of weather modification is intentional weather modification. Intentional in such a way that there are practical methods applied in order to force/alter the weather condition. For example, frost prevention on crops. Farmers normally utilize large fans to get the warmer air from above to mix with the cold air near the ground surface. By doing so, crops are kept from being ruined by frost.

b. 46 km/hr

Explanation:

Applying,

S' = d'/t' Equation 1

Where S' = Average speed of the bus, d' = Total distance covered by the bus, t' = Total time taken.

From the question,

d' = (100+55+75) km = 230 km

t' = (2+1+2) = 5 hours

Substitute these values into equation 1

S' = 230/5

S' = 46 km/hr.

Hence the correct option is b. 46 km/hr