csatmedium
In a Zoo, there are some Dears and Ducks. If the heads are counted, they are 180, while the legs are
- 448.What will be the number of Dears in the Zoo?
- A.136
- B.68
- C.44
- D.22
▶ Answer & Explanation
Correct answer: C. 44
Let D be the number of deers and U be the number of ducks. Each deer has 1 head and 4 legs. Each duck has 1 head and 2 legs. We are given that the total number of heads is 180, so D + U = 180. The total number of legs is 448, so 4D + 2U = 448. We can solve these two equations simultaneously. Multiply the first equation by 2: 2D + 2U = 360. Subtract this from the second equation: (4D + 2U) - (2D + 2U) = 448 - 360. This simplifies to 2D = 88, so D = 44. Therefore, there are 44 deers.
Source: UPSC csat 2020