Question: Material A costs $3 per kilogram, and Material B costs $5 per kilogram. If 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B, is x > y ?
(1) y > 4
(2) The cost of the 10 kilograms of Material K is less than $40.
- Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
- Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
- BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
- EACH statement ALONE is sufficient.
- Statements (1) and (2) TOGETHER are not sufficient.
“Material A costs $3 per kilogram, and Material B costs $5 per kilogram” is a topic of the GMAT Quantitative reasoning section of GMAT. The GMAT Data Sufficiency question is represented by a problem statement and two factual statements. This definite GMAT data sufficiency question tests the candidates' numerical proficiency and calculative skills in mathematics. GMAT Quant section contains 31 multiple-choice questions and the time limit is 62 minutes. GMAT data sufficiency comprises 15 questions out of these 31 GMAT quant questions which are two-fifths of the entire sum of questions. The candidates can improve their understanding by answering more questions from the book named “501 GMAT Questions”.
Solution and Explanation:
Approach Solution 1:
The problem statement states that:
Given:
- Material A costs $3 per kilogram
- Material B costs $5 per kilogram
- 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B i.e x+y = 10
Find out:
- If the value of x is greater than the value of y.
- The statement implies that y > 4.
If the value of y is equal to 4.5, then x=5.5 (since x+y=10)
Therefore the value of x is greater than the value of y. Thus the answer to this problem is Yes.
If the value of y is equal to 6, then x=4 (since x+y=10)
Therefore the value of x is less than the value of y. Thus the answer to this problem is No.
Therefore, the statement alone is not sufficient to answer the problem.
- The statement indicates that the expense of the 10 kilograms of Material K is less than $40
Therefore from this statement, we can conclude that 3x+5y < 40
Since x+y= 10 that is y= 10-x, then by putting the value of y in the equation we get,
3x+ 5(10-x) < 40
2x > 10
x > 5
Therefore, x > y
Hence the statement alone is sufficient to answer this question.
Correct Answer: (B)
Approach Solution 2:
The problem statement states that:
Given:
- Material A costs $3 per kilogram
- Material B costs $5 per kilogram
- 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B i.e x+y = 10
Find out:
- If the value of x is greater than the value of y.
According to the question,
x kilograms are priced at 3$ per Kilogram and y kilograms are priced at 5$ per Kilogram
Let both these x kilograms and y kilograms produces10 kilograms at z$ per Kilogram
Further, it is given that, x+y=10
Therefore the equation would be : 3(x)+5(y)=10(z)
Now let's analyse the statements:
- Statement (1) states y>4.
It is required to note the fact that x+y=10.
Therefore the value of x could vary between 0 and 6.
Hence the statement alone is insufficient
- Statement (2) indicates that the cost of the 10 kilograms of Material K is less than $40.
Therefore, we can write it as 3(x)+5(y)<40.
As we know x+y=10, then x=10−y.
Therefore, 3(10−y)+5(y) < 40
=> 30−2y+5y<40
=> 2y<10
=> y<5
If the value of y is less than 5 then the value of x is greater than 5.
Therefore, x>y
Hence the statement alone is sufficient.
Correct Answer: (B)
Approach Solution 3:
The problem statement informs that:
Given:
- Material A costs $3 per kilogram
- Material B costs $5 per kilogram
- 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B i.e x+y = 10
Find out:
- If the value of x is greater than the value of y.
- The statement cites that y > 4
If y =4.5 then x=5.5
Therefore, x>y
However, if y= 5.5, then x= 4.5
Hence, the value of x is not greater than y.
- The statement implies that the cost of the 10 kilograms of Material K is less than $40.
Therefore, we can say, 3x + 5y <40
We can rewrite the equation as 3x + 3y + 2y < 40
=> 3(x + y) + 2y < 40
Since x + y = 10, we can infer that:
=>3(10) + 2y < 40
=>30 + 2y < 40
=>2y < 10
Therefore, y < 5
Since the value of y is less than 5, then the value of x must be greater than 5. It is because the sum of x and y is 10.
Therefore, x>y
Hence the statement alone is sufficient.
Correct Answer: (B)
Suggested GMAT Data Sufficiency Questions:
*The article might have information for the previous academic years, please refer the official website of the exam.