Q. If you have two straight sticks of length 7.5 feet and 3.25 feet, what is the minimum length can you measure?
(a) 0.05 foot
(b) 0.25 foot
(c) 1 foot
(d) 3.25 feet
Correct Answer – (b) 0.25 foot.
Question from UPSC Prelims 2020 CSAT Paper
Model Answer:
If you have two straight sticks of length 7.5 feet and 3.25 feet
To find the minimum length that can be measured using two straight sticks of length 7.5 feet and 3.25 feet using the Highest Common Factor (HCF) method, we can first convert the lengths to inches:
7.5 feet = 90 inches
3.25 feet = 39 inches
Then, we can find the HCF of 90 and 39:
90 = 2 * 3 * 3 * 5
39 = 3 * 13
The common factor is 3, so the HCF is 3 inches.
Therefore, the minimum length that can be measured with these two sticks is 3 inches, which is equivalent to 0.25 feet.
Hence, the correct answer is (b) 0.25 foot.
