Question

Dhiru can dig 1/a of a field in 20 hours. What fraction of the same field can kaku dig in 20 hours if the two of them can dig the field in 60 hours, working together at their respective rates?

Answer 1

Answer:

Step-by-step explanation:

In 20 hours Dhiru can dig 1/a of the field.

In 1 hours Dhiru can dig 1/a ÷20 of  the field, ie. 1/a ×1/20 = 1/20a

Kaku can dig the field in x hours.

In 1 hour kaku can dig 1/x of the field.

both of them dig the field in 60 hours.

so in 1 hour both of them dig 1/60 of the field.

therefore,

1/20a +1/x = 1/60

1/x = 1/60 - 1/20a

so in 20 hours Kaku can dig

20 ×{1/60 - 1/20a)

20 × 1/60 - 20×1/20a

1/3 - 1/a

Answer 2

Step-by-step explanation:

Dhiru digs 1/a part of field in 20 hours.

∴ Dhiru digs 1 part of field in 20a hours

= 1/60 - 1/20a = ( a - 3 ) / 60a

∴ Part of field dug by Kaku in 1 hour

= 20 ( a - 3 ) / 60a

= a - 3 / 3a