Question

Riddhi can do a work in 10 days and Siddhi can do same work in 15 days. They worked together for 2 days and then Riddhi left the work. Now in how many days Siddhi can do the remaining work alone?





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Answer 1

Answer:

Siddhi can do the remaining work alone in 10 days

Step-by-step explanation:

Given,

• Riddhi can do a work in 10 days
• Siddhi can do same work in 15 days
• They worked together for 2 days and then Riddhi left the work

To find,

• the number of days Siddhi can do the remaining work alone

Solution,

 Riddhi can do a work in 10 days

In one day, Riddhi can do (1/10) part of work

 Siddhi can do the same work in 15 days

In one day, Siddhi can do (1/15) part of work

Together in one day, they can finish

   $\sf= \dfrac{1}{10}+\dfrac{1}{15} \ part \ of \ work \\\\ = (\dfrac{1}{10} \times \dfrac{3}{3})+(\dfrac{1}{15} \times \dfrac{2}{2} ) \ part \ of \ work \\\\ =\dfrac{3+2}{30} \ part \ of \ work \\\\ = \dfrac{5}{30} \ part \ of \ work \\\\ = \dfrac{1}{6} \ part \ of \ work$

They worked together for 2 days.

So, in two days, the can finish

     = 2 × 1/6 part of work

     = 1/3 part of work

The remaining work = 1 - 1/3

            = (3 - 1)/3

            = 2/3

we have to find the number of days, Siddhi can do 2/3 of the work alone.

[ In one day, Siddhi can do 1/15 part of work ]

 

The required number of days

          $\sf =\dfrac{\dfrac{2}{3}}{\dfrac{1}{15}} \\\\ =\dfrac{2}{3} \times 15 \\\\ = 2 \times 5 \\\\ = 10 \ days$

Therefore, Siddhi can do the remaining work alone in 10 days

 

Answer 2

Answer:

10

Step-by-step explanation:

$\huge\bf\underline\blue{answer:}$

$\huge\sf\underline\green{given,}$

work done by ridhi = 10days.

work done by siddhi = 15 days.

.: one day work of ridhi = 1/10

one day work of siddhi = 1/15.

$\huge\sf\underline{to find}$

in how many days Siddhi can do the remaining work alone.

$\huge\fcolorbox{black}{pink}{solution}$

one day work done by both riddhi and siddhi together = 1/10+1/15

= (1/10×3/3)+(1/15×2/2)

= 3/30+2/30

= 5/30

= 1/6.

.: they worked for 2 days

= 2×1/6

= 1/3rd path of work.

the remaining work = 1-1/3

= 2/3.

.: sidhi can do it ,so

= 2/3×\÷1/15

= 2/3×15

= 10 days.

.: siddhi alone can do remaining work in 10days.