By increasing the speed of his car by 15 \text{ km/hr}, a person covers a distance of 300 \text{ km} by taking an hour less than before. What was the original speed of the car?
- A. 45 \text{ km/hr}
- B. 50 \text{ km/hr}
- C. 60 \text{ km/hr} ✓
- D. 75 \text{ km/hr}
Correct Answer: C. 60 \text{ km/hr}
Explanation
Let the original speed be v. According to the problem, \frac{300}{v} - \frac{300}{v+15} = 1. Solving for v, we get v^2 + 15v - 4500 = 0, which factorizes to (v-60)(v+75) = 0. Since speed must be positive, v = 60 \text{ km/hr}.
Related questions on Arithmetic
- What is the remainder when (17^{25} + 19^{25}) is divided by 18?
- A bottle contains spirit and water in the ratio 1:4 and another identical bottle contains spirit and water in the ratio 4:1. In what rat...
- Let P = 5^5 \times 15^{15} \times 25^{25} \times 35^{35} and Q = 10^{10} \times 20^{20} \times 30^{30} \times 40^{40}. What is the numbe...
- Two students X and Y appeared in a test. The score of X is 20 more than that of Y. If the score of X is 75% of the sum of the scores of X an...
- Question: The product of a natural number N and the number M written by the same digits of N in the reverse order is 252. What is the number...