The average of 12 numbers is 40. The average of the first 6 numbers is 35 and the average of the next 5 numbers is 45. If the 11th number is 5 less than the 12th number, then what is the average of the 11th and 12th numbers?

Correct option is A

Total = 12 × 40

= 480

Sum of 1st six numbers = 6 × 35

= 210

Sum of next five numbers = 5 × 45

= 225

Last (12^th) numbers = 480 - 210 - 225 = 45

So, 11th = 45 – 5 = 40

Required average = $$\frac{40+45}{2}$$​ = 42.5