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GATE CS 2019 · General Aptitude

Question 4

MCQPrinted as GA Q.41 markWrong answer: −1/3Easy (estimate)

Question

Ten friends planned to share equally the cost of buying a gift for their teacher. When two of them decided not to contribute, each of the other friends had to pay Rs 150 more. The cost of the gift was Rs. _____.

Choose one option
Official answer and solution
Official answer
C
From
Official GATE 2019 answer key

Solution

Formulate a linear equation relating the total gift cost to the per-person contribution.

Let the total cost of the gift be CC rupees.

Originally, 10 friends planned to share the cost equally, so each friend's planned share was:

S1=C10S_1 = \frac{C}{10}

When 2 friends backed out, 10−2=810 - 2 = 8 friends remained to share the cost, so each remaining friend paid:

S2=C8S_2 = \frac{C}{8}

We are given that S2−S1=150S_2 - S_1 = 150:

C8−C10=150  ⟹  C(5−440)=150  ⟹  C40=150\frac{C}{8} - \frac{C}{10} = 150 \implies C \left(\frac{5 - 4}{40}\right) = 150 \implies \frac{C}{40} = 150

Solving for CC:

C=150×40=6000 rupeesC = 150 \times 40 = 6000\text{ rupees}
Final answer

C

The answer is the one in the official GATE answer key. The solution is this site's own explanation.

Source

Paper
GATE 2019 Computer Science and Information Technology (CS)
Question
4 of 65, printed as GA Q.4
Section
General Aptitude

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