GIven: In the 12th innings, Sachin Tendulkar scores = 120 runs Formula used: Average = sum of all numbers/total number Calculation: Let Sachin Tendulkar, average scores in 11th innings be x Total runs in 11th innings =11×x ⇒11x After increasing the average by 5 runs, new average =x+5 ⇒ (Total runs in 11th innings + runs in 12th innings)/12 = x + 5 ⇒(11x+120)/12=x+5 ⇒(11x+120)=(x+5)×12 ⇒11x+120=12x+60 ⇒12x–11x=120–60 ⇒x=60 New average =60+5 ⇒ 65 ∴ The new average is 65. Actually after scoring 120 runs in 12th innings the average increased by 5 runs. then total increased runs =12×5=60 runs Now previous average should be 120−60 ⇒ 60 runs New average = 60 + increased average ⇒ New average =60+5 ⇒ 65 runs ∴ The new average is 65.