Problem: the average of 10 numbers is 40.2 . later it is found that two numbers have been wrongly copied . the first is 14 greater than the actual number and the second number added is 13 instead of 31 . find the correct average .
Rationale: "sum of 10 numbers = 402 corrected sum of 10 numbers = 402 – 13 + 31 – 14 = 406 hence , new average = 406 ⁄ 10 = 40.6 answer c"
annotated_formula: divide(subtract(add(multiply(40.2, 10), add(13, 14)), 31), 10)