A car travels a distance of 45 km at the speed of 15 km/hr. It covers the next 50 km of its journey at the speed of 25km/hr and the last 25 km of its journey at the speed of 15 km/hr. What is the average speed of the car?
Answer: Option D. We know, Average speed = Total distance travelled / Total time taken Average = 45+50+25/3+2+25/15= 18kmph.
A car travels a distance of 170 km in 2 hours partly at a speed of 100 km/h and partly at 50 km/h. The distance travelled at a speed of 50 km/h is
Answer: Option C. Suppose he covers x km at 100 kmph he covers 170-x at 50 kmph
Solving this equation, we get x = 140. he covers 30km at 50 kmph.
Even after reducing the marked price of a transistor by Rs. 32, a shopkeeper makes a profit of 15%. If the cost price be Rs. 320, what percentage of profit would he have made if he had sold the transistor at the marked price?
None of these
Answer: Option A. Let x be the marked price, So x - 32 = 320 × 1.15 ⇒ x = 400. So required value is 400 = 320 (1 + profit/100), So profit is 25%
The sum of five numbers is 260. The average of first two numbers is 30 and average of the last two numbers is 70. What is third number?
None of these
Answer: Option E. (a + b + c + d + e)/5 = 260 ...........(1) (a + b)/2 = 30 , Therefore a + b = 60 (d + e)/2 = 70 , Therefore d + e = 140 Using the values in (1) , We get c= 60 As sum of first two is 60 & sum of last two is 140 so third no. is 260 - 60 - 140 = 60.
20 boys and 32 girls form a group for social work. During their membership drive same no. of boys and girls joined the group. How many members does the group have now, if the ratio of boys to girls is 3:4 respectively?
Answer: Option E. Let x be the new boys as well as girls , Therefore Solving this we get x = 16 So total will be 36 + 48 = 84