If 5 men take 8 days to type 10 books, then how many days does it take

If 5 men take 8 days to type 10 books, then how many days does it take for 8 men to type 2 books?

Answer»

Here the 3 quantities are men, books typed and number of days.

Let the number days taken to type 2 books by 8 men be x.

From the above,

Here number of days depends on both men and number of books typed.

So, we have to take compound ratio of

8 : 5 and 10:2.

8 : x = 8 × 10 : 5 × 2

Since the ratios are equal,

The product of means = The product of extremes

⇒ 8 : x = 80 : 10

⇒ x × 80 = 8 × 10

⇒ 80x/80 = 80/80

⇒ x= 1 day Or

x = 5/8 x 2/10 x 8 = 1

∴ Number of days taken to type 2 books by 8 men is 1.