Question

4 oxen or 12 cows can graze a field in 32 days. How long would 7 oxen and 3 cows take to graze the same field?

• A. 12 days
• B. 17 days
• C. 32 days
• D. 16 days

Answer 1

The correct option is D

16 days

4 oxen = 12 cows

$\Rightarrow$ $1$ ox = $\frac{12}{4}$ cows

$\Rightarrow 7\text{oxen}\equiv \frac{12}{4}\times 7\text{cows}=21\text{cows}$

$\Rightarrow$ (7 oxen + 3 cows) $\equiv$ (21 cows + 3 cows) = 24 cows

Now, 12 cows can graze the field in 32 days.

So, 1 cow can graze the field in $(32\times 12)$ days.
[less cows, more days]

24 cows can graze the field in $\frac{32\times 12}{24}=16days$
[more cows, less days]

Hence, 9 oxen and 3 cows can graze the field in 16 days.