Bunuel
Bob the bodybuilder is training for a competition to be held on 10th of April. On the 1st April he trains for 2 hours and on 2nd April he trains for 4 hours and on 3rd April he trains for 6 hours. He keeps on increasing his training time till he reaches 14 hours per day and then keeps it constant at 14 hours a day. How many hours did he train between 1st April, inclusive and 10th April, exclusive?
A. 80
B. 82
C. 84
D. 86
E. 88
Bob trains for even number of hours for 7 days and then he continues at 14 hours a day.
Sum of first n even numbers is expressed as \(n*(n+1)\). Sum of hours from day 1 to day 7=\(7*(7+1)=56\) hours.
Sum of hours from 8 to 10 =\(14*3=28\) hours.
Total hours from day 1 to day 10=\(56+42=98\) hours.
Excluding 1st and 10th day, total sum of hours =\(98-(2+14)=82\) hours.
That is our answer.
IMO, Option B.
If you read the question carefully, it says that the training on 1st April is inclusive. Hence, we will have to include the 2 hours from there as well. And the total would come up to 84 hours. Therefore, the answer should be C.