Question

the average of 30 number is 68 the average of first 7 number is 63 and the last 7 number is 70 what is the 7th number​

Answer 1

Answer:

Sum of 6 numbers =60×30=180

Sum of first 4 numbers =4×25=100

Sum of last 3 numbers =3×35=105

∴ Fourth number =(100+105)−180

                               =205−180

                               =25