The average of 7 numbers is 30. the average of the first to the fourth numbers is 32, the average of the third to the seventh numbers is 27. What is the sum of the third and the fourth numbers? I want the answer please.
Here is what you know:
x1 + x2 + x3 + x4 = 32*4 = 128
x3 + x4 + x5 + x6 + x7 = 27*5 = 135
x1 + x2 + x3 + x4 + x5 + x6 + x7 = 7*30 = 210
From the first and third equation:
x5 + x6 + x7 = 210 - 128 = 82
From the second equation and the one above:
x3 + x4 = 135 - 82 = 53