BTGmoderatorLU wrote:Source: GMAT Club Tests

50% of the factory workers are not older than 30 years old. What percent of the factory workers are younger than 40 years old?

1. 30% of the factory workers are older than 30 but younger than 40 years old.
2. 20% of the factory workers are at least 40 years old.

The OA is D.

Given: 50% of workers = less than equal to 30 years
Question: What percent of workers are less than 40 years?

Let's take each statement one by one.

1. 30% of the factory workers are older than 30 but younger than 40 years old.

=> 30% of workers = (30-40)

Thus, the percentage of workers less than 40 years
= the percentage of workers less than equal to 30 years + the percentage of workers between 30 and 40
= 50 + 30 = 80%. Sufficient

2. 20% of the factory workers are at least 40 years old.

=> 20% of workers = more than equal to 40 years

Thus, the percentage of workers less than 40 years = 100 - 20% = 80%. Sufficient.

The correct answer: D

Hope this helps!

-Jay
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