A runner, training for a competition, ran on a track every day for 10 weeks. The first week he ran 8 kilometers each day of the week. The second week he increased his daily run by one lap (400 meters). The third week he increased again his daily run by one lap and so on. What is total distance he ran in 10 weeks?

Total = 686000 meters for 10 weeks 7 days a week.

Step-by-step explanation:

Let's solve this by doing the increase on just 1 training day per week. Then we can find the grand total for 7 days a week by multiplying by 7

a = 8000

n = 10

d = 400

Sum = (a + L) * n/2

L = a + (n - 1) * d L = 8000 + (10 - 1) * 400 L = 8000 + 9*400 L = 8000 + 3600 L = 11600 meters

Sum = (8000 + 11600) * 10/2

Sum = 19600 * 10/2

Sum = 98000 meters.

This total represents 1 training day a week.

The total amount is 7 times this figure.

Total = 7 * 98000 = 686 000 meters.