Question

average of 8 numbers is 31,seven of them are 15,45,17,19,33,48,65. what is the eight number?​

Answer 1

Answer:

The eighth number is 6

Step-by-step explanation:

Average = sum of observations / no. of observations

Sum of observations = Average * no. of observations

Sum of 7 observations = 242

Average of all 8 observations = 31

=> Sum of all 8 observations = 31*8 = 248

Eighth observation = Sum of 8 observations - sum of 7 observations

                                = 248 - 242

                                = 6

Answer 2

Step-by-step explanation:

let eight number be x

15+45+17+19+33+48+65+x=31 × 8

242+x=31 × 8

x=(31×8) - 242

x=248 - 242

x= 6