Advertisements
Advertisements
प्रश्न
A and B can do a piece of work in 18 days; B and C in 24 days and A and C in 36 days. In what time can they do it, all working together?
Advertisements
उत्तर
\[\text{ Time taken by } \left( A + B \right) \text{ to do the work = 18 days } \]
\[\text{ Time taken by } \left( B + C \right) \text{ to do the work = 24 days } \]
\[\text{ Time taken by } \left( A + C \right) \text{ to do the work = 36 days } \]
\[\text{ Now } , \]
\[\text{ Work done by } \left( A + B \right) = \frac{1}{18}\]
\[ \text{ Work done by } \left( B + C \right) = \frac{1}{24}\]
\[ \text{ Work done by } \left( A + C \right) = \frac{1}{36}\]
\[ \therefore \text{ Work done together } = \left( A + B \right) + \left( B + C \right) + \left( A + C \right)\]
\[ = \frac{1}{18} + \frac{1}{24} + \frac{1}{36}\]
\[ = \frac{4 + 3 + 2}{72} = \frac{9}{72}\]
\[ = \frac{1}{8}\]
\[ \therefore \text{ Work done together } = 2\left( A + B + C \right) = \frac{1}{8}\]
\[ \therefore \text{ Work done by } \left( A + B + C \right) = \frac{1}{16}\]
\[ \text{ Thus, together they can finish the work in 16 days } .\]
APPEARS IN
संबंधित प्रश्न
In which of the following tables x and y vary directly?
(i)
| a | 7 | 9 | 13 | 21 | 25 |
| b | 21 | 27 | 39 | 63 | 75 |
(ii)
| a | 10 | 20 | 30 | 40 | 46 |
| b | 5 | 10 | 15 | 20 | 23 |
(iii)
| a | 2 | 3 | 4 | 5 | 6 |
| b | 6 | 9 | 12 | 17 | 20 |
(iv)
| a | 12 | 22 | 32 | 42 | 52 |
| b | 13 | 23 | 33 | 43 | 53 |
Aasheesh can paint his doll in 20 minutes and his sister Chinki can do so in 25 minutes. They paint the doll together for five minutes. At this juncture they have a quarrel and Chinki withdraws from painting. In how many minutes will Aasheesh finish the painting of the remaining doll?
Working 8 hours a day, Ashu can copy a book in 18 days. How many hours a day should he work so as to finish the work in 12 days?
A pipe can fill a cistern in 10 hours. Due to a leak in the bottom it is filled in 12 hours. When the cistern is full, in how much time will it be emptied by the leak?
If 7 kg onions cost 140 rupees, how much must we pay for 12 kg onions?
An auto rickshaw takes 3 hours to cover a distance of 36 km. If its speed is increased by 4 km/h, the time taken by it to cover the same distance is ______.
If x and y are in direct proportion, then (x – 1) and (y – 1) are also in direct proportion.
Write whether the following statement vary directly, vary inversely with each other, or neither of the two.
Distance travelled by an auto-rickshaw and time taken.
The table shows the time four elevators take to travel various distances. Find which elevator is fastest and which is slowest.
| Distance (m) | Time (sec.) | |
| Elevator- A | 435 | 29 |
| Elevator- B | 448 | 28 |
| Elevator- C | 130 | 10 |
| Elevator- D | 85 | 5 |
How much distance will be travelled by elevators B and C separately in 140 sec? Who travelled more and by how much?
The following table shows the distance travelled by one of the new eco-friendly energy-efficient cars travelled on gas.
| Litres of gas | 1 | 0.5 | 2 | 2.5 | 3 | 5 |
| Distance (km) | 15 | 7.5 | 30 | 37.5 | 45 | 75 |
Which type of properties are indicated by the table? How much distance will be covered by the car in 8 litres of gas?
