Multiple choice

Passage

Directions: The data below provides information about two cars, P and Q, travelling from city M to city N at the same speed. Read the data carefully and answer the following question. Car P: Car P departs from city M and, after travelling 80 km, reduces its speed by 20%. The car reaches city N at 2:00 P.M. Car Q: Car Q departs from city M at the same time as Car P and, after travelling 425 km, reduces its speed by 40%. The car reaches city N at 1:30 P.M. If both cars travelled with their original speeds, then they will reached city N at 12:00 P.M.

Find the sum of time taken by car P and car Q to cover the distance between city M & N, if both cars cover the total distance at their original speed.

  1. 14 2 3 hours

  2. 15 1 3 hours

  3. 18 2 3 hours

  4. 16 hours

  5. 18 hours
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let original speed be v and distance be D. From Car P: 80/v + (D-80)/(0.8v) = D/v + 2, giving D = 80 + 8v. From Car Q: 425/v + (D-425)/(0.6v) = D/v + 1.5, giving D = 425 + 2.25v. Solving yields v = 60 km/hr and D = 560 km. Each car takes 560/60 = 28/3 hours, so the sum is 56/3 = 18 and 2/3 hours.

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