It is given that the number of portraits painted in 8 hours is 600.
It is required to calculate the number of portraits that will be painted in 4 minutes.
Calculate the rate by dividing the number of painted portraits by the number of hours:

Since it is required to find the number of portraits that will be painted in 4 minutes, convert 8 hours to minutes by multiplying by 60, in order to get the rate in portraits per minute:

Multiply the rate in portraits per minute by the time, 4 minutes to get the number of portraits that will be painted in 4 minutes:

The number of portraits that would be painted in 4 minutes is 5.