The speed of a car increases by 2 kms after every one hour. If the distance travelling in the first one hour was 35 kms. what was the total distance travelled in 12 hours?

Total distance travelled in 12 hours =(35+37+39+.....upto 12 terms) This is an A.P with first term, a=35, number of terms, n= 12,d=2. Required distance = 12/2[2 x 35+{12-1) x 2] =6(70+23) = 552 kms.