Question

While Flinn was starting the fire, his friends were collecting firewood. Flinn has 5 sticks. If he puts 3 sticks in the fire every minute, and his friends bring 7 sticks every minute, how many minutes will they need to make a pile of 45 sticks next to their fire?

Answer 1

Answer:

Time required to make a pile of 45 sticks next to fire =10 minutes.

This is example of A. P

Firdt yerm 5-3+7=9 sticks.

Common difference = 7-3 = 4

So number of sticks next to fire is increasing like this 9,13 17,21...

nth term of AP = a + (n-1) d we need to find n

a+(n-1)d=45

9+(n-1) 4 =45

(n-1) 4 = 36

(n-1)=9

n=10.