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If 40 percent of the people who bought a particular smartphone bought a smartwatch, what percent of the smartphone buyers bought headphones?
(1) 50 percent of people who bought the smartphone and the smartwatch also bought headphones.
(2) 80 percent of people who bought the smartphone and the headphones also bought the smartwatch.
Correct answer: C
Evaluation by MS:
Quality – 4
Difficulty – 3
Topic – Word Problem
To be included in CBTs? – No
= = = = = = = = = = = = = = = = = = = = = =
Explanation: Let P be the event that a person buys a smartphone.
Let W be the event that a person buys a smartwatch.
Let H be the event that a person buys headphones.
40 percent of the people who bought a particular smartphone bought a smartwatch, which can be expressed as: P Ո W = 0.4P (Equation I)
We have to find what percent of the smartphone buyers bought headphones, which can be expressed as: What percent of P is (P Ո H)?
We need to find whether the value of “100 x (P Ո H)/P” can be determined. Statement (1) 50% x (P Ո W) = (P Ո W Ո H)
From Equation I:
50% x 0.4P = (P Ո W Ո H)
0.5 x 0.4P = (P Ո W Ո H) (Equation II)
Since it is
not possible to express (P Ո H) in terms of P from the given information, it is NOT possible to determine with certainty the percentage of smartphone buyers that bought headphones.
Hence, Statement (1) is insufficient. Statement (2) 80% x (P Ո H) = (P Ո W Ո H)
0.8 x (P Ո H) = (P Ո W Ո H) (Equation III)
Since it is
not possible to express (P Ո H) in terms of P from the given information, it is NOT possible to determine with certainty the percentage of smartphone buyers that bought headphones.
Hence, Statement (2) is insufficient. As Statement (1) alone as well as Statement (2) alone is insufficient to answer the question, we need to now combine the two statements.
Statement (1) and Statement (2) combined From Equation II and Equation III,
0.5 x 0.4P = 0.8 x (P Ո H)
(P Ո H)/P = (0.5 x 0.4)/0.8
It is possible to determine the exact percentage of smartphone buyers that bought headphones.
Hence, Statement (1) and Statement (2) combined are sufficient. C is the correct answer choice.