QUESTION

CSAT

Medium

Reasoning

Prelims 2020

If you have two straight sticks of length 7.5 feet and 3.25 feet, what is the minimum length can your measure?

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Explanation

Given:

Length of stick S1 = 7.5 feet Length of stick S2 = 3.25 feet To determine the minimum length we can measure, we use stick S2 to measure the length of stick S1. By doing so, we get:

Total length of S1 = 3.25 + 3.25 + remaining length of S1 6.56.5 + remaining length of S1 = 7.57.5 Therefore, the remaining length of S1 = 7.56.5=17.5 – 6.5 = 1 foot Thus, the minimum length that can be measured is 1 foot.

Note: If the question had asked, "What are the minimum possible pieces of equal size that we can make by cutting the two sticks?", we would solve it as follows:

Length of stick S1 = 7.5 feet = 152\frac{15}{2} feet Length of stick S2 = 3.25 feet = 134\frac{13}{4} feet The maximum possible size of a piece would be the HCF of (152\frac{15}{2} and 134\frac{13}{4}):

HCF of (15, 13) = 1, and LCM of (2, 4) = 4 So, the maximum size of each piece = 14\frac{1}{4} = 0.25 feet The number of minimum possible pieces of equal size is:

(7.5+3.25)/0.25=43(7.5 + 3.25) / 0.25 = 43 pieces.

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