Question
Train ‘A’ running with a speed of 54 km/hr. can
cross a standing goods train of 4 times its length in 20 seconds. Find the time taken by 240 meters long train ‘B’ which is coming from the opposite direction of train ‘A’, with a speed of 9 m/s, to cross-train ‘A’.Solution
Let the length of train ‘A’ be ‘x’ meters. Therefore, the length of the goods train = ‘4x’ meters Speed of train ‘A’ = 54 × (5/18) = 15 m/s According to the question, 4x + x = 15 × 20 => 5x = 300 => x = 60 Therefore, the time is taken by train ‘B’ to cross train ‘A’ = {(60 + 240)/ (15 + 9)} = 300/24=50/4=12.5second
There are 15 numbers such that average of first 12 numbers is 50 while the average of last five numbers is 60. Find the 12th number, if the ratio betwee...
Find the mean of the following observations:
45, 54, 42, 56, 46, 48, 52, 50, 57, 43The average weight of a family of 6 members is 72 kg. If the oldest member dies, the average weight of the family decreases by 1.6 kg. Find the weight o...
The average age of 13 girls is 40 years. If the age of one more girl is added the average decreases by half a year. What is the age of new girl?
The average wage of a group of 25 labourers is Rs. 470. If 4 persons receiving average wage of Rs. 350 leave the group and 2 persons receiving average w...
The average mark obtained by 110 candidates in a certain examination is 45. If the average marks of passed candidates are 50 and that of the failed cand...
The average of five consecutive odd numbers is 45. What is the average of the first three numbers among them?
- The number of students in class 'A' is 100, and the ratio of the number of girls to boys is 2:3. If the average number of boys in classes A and B is 105, a...
The average of 8 numbers is 12. If the 2 is added in 1st number, 4 is added in 2nd number, 8 is added in 3rd number and in the same way the number are a...
The average age of three children is 20 years. If their ages are in the ratio 2:3:5. Find the age of the youngest child.
