High School

Three seniors or seven juniors can finish a work in 32 days. How many days will it take for seven seniors and five juniors to finish the same work?

Answer :

In 24 days 7 seniors and 5 juniors will finish the work.

Let's define the following variables:

  • - x: The number of days it takes for one senior to finish the work alone
  • - y: The number of days it takes for one junior to finish the work alone

Given information:

  • - 3 seniors or 7 juniors finish the work in 32 days.

We can set up the following equations:

  • 3/x = 1/32 (1)
  • 7/y = 1/32 (2)

From equation (1), we get:

x = 32/3 = 96

From equation (2), we get:

y = 32/7 = 128/7

Now, we need to find the number of days it takes for 7 seniors and 5 juniors together to finish the work.

Let z be the number of days it takes for 7 seniors and 5 juniors together to finish the work.

We can use the principle of inverse summation of work rates:

(7/x) + (5/y) = 1/z

Substituting the values of x and y, we get:

(7/96) + (5/128) = 1/z

1/z = (7/96) + (35/128)

1/z = (105/1536) + (35/128)

1/z = (3465/12288) + (2730/12288)

1/z = 6195/12288

z = 12288/6195

z = 24 days

Therefore, 7 seniors and 5 juniors together will finish the work in 24 days.