The average of 10 numbers is 40.2. Later it is found that two numbers have been wrongly copied. The first is 15 greater than the actual number and the second number added is 13 instead of 31. Find the correct average.  Choose the most appropriate option.
A) 40.2
B) 40.4
C) 40.5
D) 40.8
E) none of the above

Rationale: "sum of 10 numbers = 402 corrected sum of 10 numbers = 402 – 13 + 31 – 15 = 405 hence , new average = 405 ⁄ 10 = 40.5 answer c"
Answer: C