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Q26·CSAT · Prelims 2022

Calculating intervals and distance between equidistant plants

NumericalArithmetic Word ProblemsFactual singleMedium

Question

On one side of a 1.01 km long road, 101 plants are planted at equal distance from each other. What is the total distance between 5 consecutive plants?

Options

a

40 m

b

40.4 m

Answer
c

50 m

d

50.5 m

Explanation

Convert the total road length into meters: 1.01 km = 1010 m.

If there are 101 plants planted from the very beginning to the very end of the road, they create exactly ⟨MATH⟩101 - 1 = 100⟨/MATH⟩ equal intervals (gaps) between them. Length of one gap = 1010 m / 100 = 10.1 m.

The distance between 5 consecutive plants spans exactly ⟨MATH⟩5 - 1 = 4⟨/MATH⟩ gaps. Total distance = 4 × 10.1 m = 40.4 m.

The "fencepost error" rule dictates that N objects in a straight line create exactly N-1 intervals. Always divide total distance by N-1, not N.

Answer: (b).

Question details

Year

2022

Paper

CSAT

Question

Q26

Section

Numerical Ability

Sub-topic

Arithmetic Word Problems

Type

Factual single

Difficulty

Medium

Source hint

101 plants on a 1.01 km long road

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