Question
What is the unit digit of the sum of first 111 whole
numbers?Solution
Sum of first 11 whole numbers is 0+1+2...110 i.e n(n+1)/2 =110*111/2 =55*111 Therefore unit digit is 5
If a car runs at 36 km/hr, it reaches its destination late by 15 minutes but if runs at 45 km/hr it is late by 9 minutes. What is the correct time for t...
- Two buses, ‘D’ and ‘E’, started from cities ‘A’ and ‘B’ towards each other at the same time. When they met after 10 hours, bus ‘E’ had ...
A train covers a certain distance at a speed of 24 km/h and the next same distance with a speed of 30 km/h and the next same distance with a speed of 40...
Ratio of speeds of ‘A’ and ‘B’ is 6:11, respectively. If they participate in a 220-metre race and ‘B’ gives ‘A’, a head start of ‘m’...
- A car was driven for 2.5 hours at a speed of 100 km/h and then for 1.5 hours at a speed of 80 km/h. Find the car's average speed for the total journey.
John travelled a total distance of 432 km. He covered 5/8 of this distance at a constant speed of 30 km/h. To complete the entire journey in 13.5 hours,...
A train has to cover a distance of 90 km in 15 hours. If it covers half the journey in 4/5 th of the time, the speed to cover remaining distance in the ...
Driving at 3/5 of my original speed I am 4 hours late for my office. What is my original time taken (km/h)?
A man travelled a total distance of 300 km. He travelled first 100 km on car with a speed of 20 km/h and rest of the distance on bike whose speed is 10 ...
A goods train and a passenger trains are running on parallel tracks in the same direction.The driver of the goods train observes that the passenger tra...
