A municipality made a tank for water preservation and added pumps with it. The pumps separately can fill the empty tank in 15 , 20 and 30 hours respectively. Today when the 3 pumps started together at 7 am , 2 3 part of the tank was filled with water. After 1 hour the first pump and after 2 more hours the third pump was stopped. Let's calculate when the tank was totally filled up.

One hour of work of three pipes separately 1 15 , 1 20 , 1 30 . Three pipes started working for 1 hour. 1 hour work of all the three together is 1 15 + 1 20 + 1 30 1 15 + 1 20 + 1 30 = 4 + 3 + 2 60 = 9 60 = 3 20 Remaining work = 1 - 3 20 = 17 20 After 1 hour only two pipes worked Remaining two pipes work for one hour = 1 20 + 1 30 = 3 + 2 60 = 5 60 = 1 12 Their both work for 2 hours = 2 × 1 12 = 1 6 Remaining work 17 20 - 1 6 = 51 - 10 60 = 41 60 Remaining work done by thirds pipe alone for 60 41 = 1 . 46 hours Total time = 1 + 2 + 1 . 46 = 4 . 46 hours Actual time = 7 + 4 . 46 = 11 . 46 hours Tank filled at 11 . 46 hours .

A municipality made a tank for water preservation and added pumps with it. The pumps separately can fill the empty tank in 15 , 20 and 30 hours respectively. Today when the 3 pumps started together at 7 am , 2 3 part of the tank was filled with water. After 1 hour the first pump and after 2 more hours the third pump was stopped. Let's calculate when the tank was totally filled up. Let's calculate how much of the tank the second pump filled up.

One hour of work of three pipes separately 1 15 , 1 20 , 1 30 . Three pipes started working for 1 hour. 1 hour work of all the three together is 1 15 + 1 20 + 1 30 1 15 + 1 20 + 1 30 = 4 + 3 + 2 60 = 9 60 = 3 20 Remaining work = 1 - 3 20 = 17 20 After 1 hour only two pipes worked Remaining two pipes work for one hour = 1 20 + 1 30 = 3 + 2 60 = 5 60 = 1 12 Their both work for 2 hours = 2 × 1 12 = 1 6 Remaining work 17 20 - 1 6 = 51 - 10 60 = 41 60 Hence, 41 60 part of the tank filled by pipe 2 .

E M B I B E

Ganitprabha (MATHEMATICS TEXT BOOK) Class 8>Chapter 17 - Time and Work>Let's work out 17.2>Q 9

HARD

8th West Bengal Board

IMPORTANT

Earn 100

Mary and David can do a work individually in $10 days, 15 days$ respectively. At first mary alone worked for $4$ days, then David alone worked for $5$ days and left. Maria came and completed the remaining work in $4$ days. If Mary, David and Maria would work together, let's calculate in how many days they would complete the work.

Important Questions on Time and Work

HARD

8th West Bengal Board

IMPORTANT

Ganitprabha (MATHEMATICS TEXT BOOK) Class 8>Chapter 17 - Time and Work>Let's work out 17.2>Q 10

A municipality made a tank for water preservation and added pumps with it. The pumps separately can fill the empty tank in

15, 20 and 30

hours respectively. Today when the

3

pumps started together at

7 am

,

\frac{2}{3}

part of the tank was filled with water. After

1

hour the first pump and after

2

more hours the third pump was stopped. Let's calculate when the tank was totally filled up.

HARD

8th West Bengal Board

IMPORTANT

Ganitprabha (MATHEMATICS TEXT BOOK) Class 8>Chapter 17 - Time and Work>Let's work out 17.2>Q 10

A municipality made a tank for water preservation and added pumps with it. The pumps separately can fill the empty tank in

15, 20 and 30

hours respectively. Today when the

3

pumps started together at

7 am

,

\frac{2}{3}

part of the tank was filled with water. After

1

hour the first pump and after

2

more hours the third pump was stopped. Let's calculate when the tank was totally filled up. Let's calculate how much of the tank the second pump filled up.

HARD

8th West Bengal Board

IMPORTANT

Ganitprabha (MATHEMATICS TEXT BOOK) Class 8>Chapter 17 - Time and Work>Let's work out 17.2>Q 10

A municipality made a tank for water preservation and added pumps with it. The pumps separately can fill the empty tank in

15, 20 and 30

hours respectively. Today when the

3

pumps started together at

7 am

,

\frac{2}{3}

part of the tank was filled with water. After

1

hour the first pump and after

2

more hours the third pump was stopped. Let's calculate when the tank was totally filled up. Let's calculate how much of the tank the second pump filled up. When the third pump is stopped, let's calculate how much of the tank was filled with water.

HARD

8th West Bengal Board

IMPORTANT

Ganitprabha (MATHEMATICS TEXT BOOK) Class 8>Chapter 17 - Time and Work>Let's work out 17.2>Q 11

My friend and Rina can do garden work alone in $4$ hours. I can do that work alone in $2$ hours. But if we do that work together, let's calculate how much time will be needed.

Learn and Prepare for any exam you want !

|

|

|

|

|

|

|

|