In this question, 10 people average running distance is 2.7miles. Then the sum of their running distance would be: 10 people * 2.7 miles/people= 27 miles.
The group then divided into 2, 4 people with 3 miles average and 6 people with unknown average. Since the people are same like the 10 people group, their total running distance would be the same. The calculation would be:
total distance = group1 * average1 + group2 * average2
27 miles= 4 people * 3 miles/people + 6 people* average2
6 people * average2 = 27 miles -12 miles = 15 miles
average2= 15 miles/6people= 2.5 miles/people
<span>Let a_0 = 100, the first payment. Every subsequent payment is the prior payment, times 1.1. In order to represent that, let a_n be the term in question. The term before it is a_n-1. So a_n = 1.1 * a_n-1. This means that a_19 = 1.1*a_18, a_18 = 1.1*a_17, etc. To find the sum of your first 20 payments, this sum is equal to a_0+a_1+a_2+...+a_19. a_1 = 1.1*a_0, so a_2 = 1.1*(1.1*a_0) = (1.1)^2 * a_0, a_3 = 1.1*a_2 = (1.1)^3*a_3, and so on. So the sum can be reduced to S = a_0 * (1+ 1.1 + 1.1^2 + 1.1^3 + ... + 1.1^19) which is approximately $5727.50</span>
Since our sum is 62, and we have consecutive numbers being added, our range is most likely going to be from 10-20.
To further solve this problem easily, try finding 4 consecutive numbers with the ones place adding up to 12, 22, 32, 42, or any number that sums up to the 2 in the ones place.
Let's try 14, 15, 16, 17, since 4, 5, 6, and 7 sum up to a number with a 2 in the ones place.
14 + 15 = 29,
16 + 17 = 33.
33 + 29 is 62.
We have found the age of the friends, but we're looking for the oldest.
Our largest number is 17.
Your answer is 17 years old.
I hope this helps!
