Question

If 15 oxen or 20 cows can eat the grass of a field in 80 days, then in how many days will 6 oxen and 2 cows eat the same grass?

Answer 1

15 oxen can eat the grass in a field in 80 days
i.e 1 ox can eat the grass in a field in 1200 days
20 cows can eat the grass in a field in 80 days
i.e 1 cow can eat the grass in a field in 1600 days

Using units method, we can solve this problem
First, calculate LCM of 1200 and 1600
LCM of 1200 and 1600 is 4800
Let 4800 is the total grass of the field
An ox eats 4 units of grass in the field in a day
i.e 4800/1200= 4
A cow eats 3 units of grass in the field in a day
i.e 4800/1600= 3

Given that 6 oxen and 2 cows will eat the grass together in the field until it's finished.
6 oxen eat 24 units of grass in the field in a day
i.e 6*4 units = 24 units/day
2 cows eat 6 units of grass in the field in a day.
i.e 2*3 units = 6 units/day
As 6 oxen and 2 cows eat the grass together in a day, 30 units of grass is consumed per day
i.e 24 units per day(by 6 oxen) plus 6 units per day(by 2 cows) is 30 units
Finally, divide the total grass with units of grass consumed per day by the animals(by 6 oxen and 2 cows per day together)
i.e 4800/30= 160 days

The answer is 160 days
Hope it helps. Thanks for asking this question

Answer 2

Answer:

15 oxen take 80 days so, 6 oxen take x days

x = 15*80/6 = 200 days

20 oxen also take 80 day. So, 2 cows take y days

y = 20*80/2 = 800 days

Together work will be done in 800*200/(800+200) = 160 days

Step-by-step explanation: