3.4. If 7 men can build a house in 300 days. 3.4.1. How many men, working at the same speed, can build the same house in 70 days? 3.4.2. Is this an example of direct or indirect proportion? Give a reason for your answer.

To determine how many men are needed to build the house in 70 days, we can use the concept of "man-days." The total man-days required to build the house is 7 men multiplied by 300 days, which equals 2100 man-days. If we want to finish the house in 70 days, we divide the total man-days by the number of days: 2100 man-days ÷ 70 days = 30 men. So, 30 men working at the same speed can build the house in 70 days. This is an example of indirect proportion. As the number of days decreases, the number of men needed increases. This means that the two quantities move in opposite directions: if you want to complete the work faster (fewer days), you need more workers, showcasing the classic inverse relationship found in this type of problem.