If 5 Neptuninas can destroy 5 small plutos in 5 solar years. How long will 7…
2026
If 5 Neptuninas can destroy 5 small plutos in 5 solar years. How long will 7 Neptunians take to destroy 7 small plutos ( in solar years)?
- A.
7
- B.
5
- C.
10
- D.
12
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Show answer & explanation
Correct answer: B
Key idea: the destruction rate is proportional to the number of Neptunians.
Step 1: Find the combined rate of 5 Neptunians.
They destroy 5 plutos in 5 years, so combined rate = 5 plutos ÷ 5 years = 1 pluto per year.
Step 2: Find the rate per Neptunian.
Each Neptunian does 1 ÷ 5 = 1/5 pluto per year.
Step 3: Find the rate of 7 Neptunians.
7 Neptunians do 7 × (1/5) = 7/5 pluto per year.
Step 4: Compute the time to destroy 7 plutos.
Time = required work ÷ rate = 7 plutos ÷ (7/5 pluto/year) = 5 years.
Answer: 5 years.