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An electric bus has onboard instruments that report the total electricity consumed since the start of the trip, as well as the total distance, covered. During a single day of operation, the bus travels on stretches M, N, O, and P, in that order. The cumulative distances travelled and the corresponding electricity consumption are shown in the Table below:$$\begin{array}{|l|l|}\hline \textbf{Stretch} & \textbf{Cumulative distance (km)} & \textbf{Electricity used (kWh)} \\\hline M & 20 & 12 \\\hline N & 45 & 25 \\\hline O & 75 & 45 \\\hline P & 100 & 57 \\\hline \end{array}$$

The stretch where the electricity consumption per km is minimum is

1. $M$
2. $N$
3. $O$
4. $P$

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I am getting answer option (b) N

What is the correct answer ? but I have one answer key in which the answer is option (d) P

M = 12/20 = 0.6

N = 25/45 = 0.55

O = 45/75 = 0.6

P= 57/100 =.57

Reaching point $M$ the bus traveled $20$ km and consumed $12$ units of electricity, So, electricity consumption per km$=\frac{12}{20}.$

From point $M$ to point $N$ distance traveled $=45-20=25,$ electricity consumed  $=25-12=13.$ So, electricity consumption per km $= \frac{13}{25}.$

Likewise at point $O,$ electricity consumption per km$=\frac{20}{30}$ and at point $P$ it is $\frac{12}{25}.$ So, least electricity consumption per km is at point $P.$

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For cumulative distance and electricity:

https://www.mathsisfun.com/data/cumulative-tables-graphs.html

Electricity used is also cumulative as it is mentioned in the question -- "corresponding electricity consumption"

M - 12/20

N -  13/25

O - 20/30

P - 12/25.

So, P is the stretch with minimum consumption per km.
by

you took difference of the distance but why not the difference of KWh??
Answer is d check my explanation above

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