Question

Average of 6 no. Is 30if the avrg of 1st four is 25then that of last three is 35then the fourth is?plz help

Answer 1

Let the numbers be a1, a2, a3, a4, a5 and a6

Average of six numbers = 30

=> ( a1 +a2 +a3 + a4 +a5 +a6) / 6 = 30

=> a1 +a2 +a3 + a4 +a5 +a6 = 180 -----(1)

Average of first four numbers = 25

=> ( a1 +a2 +a3 + a4) /4 = 25

=> a1 +a2 +a3 + a4 = 100 -----(2)

On subtracting equation (2) from (1), we get

a5 + a6 = 80 ------(3)

Now,

Average of last three = 35

=> ( a4 +a5 +a6) /3 = 35

=> a4 +a5 +a6 = 105 -------(4)

On subtracting equation (3) from (4), we get

a4 = 105 - 80 = 25

a4 = 25


Fourth term = 25

Answer 2

☃️required answer ::-

Let the numbers be a1, a2, a3, a4, a5 and a6

Average of six numbers = 30

=> ( a1 +a2 +a3 + a4 +a5 +a6) / 6 = 30

=> a1 +a2 +a3 + a4 +a5 +a6 = 180 -----(1)

Average of first four numbers = 25

=> ( a1 +a2 +a3 + a4) /4 = 25

=> a1 +a2 +a3 + a4 = 100 -----(2)

On subtracting equation (2) from (1), we get

a5 + a6 = 80 ------(3)

Now,

Average of last three = 35

=> ( a4 +a5 +a6) /3 = 35

=> a4 +a5 +a6 = 105 -------(4)

On subtracting equation (3) from (4), we get

a4 = 105 - 80 = 25

a4 = 25

Fourth term = 25