GATE ECE 2015 Set 2 | GA | Question: 4

Question

An electric bulb 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 distance travelled and the corresponding electricity consumption are shown in the Table below:

$$\begin{array}{|c|c|c|} \hline \text{Stretch} & \text{Cumulative distance (km)} & \text{Electricity used (kWh)} \\ \hline M & 20 & 12 \\ \hline  N & 45 & 25 \\ \hline O & 75 & 45 \\ \hline P & 100 & 57 \\ \hline \end{array}$$

The stretches where the electricity consumption per $km$ is minimum is

• A. M
• B. N
• C. O
• D. P

Comments

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

Answer 1

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 $P.$

Answer is D

Comments

For cumulative distance and electricity:

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

Answer 2

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.

Comments

you took difference of the distance but why not the difference of KWh??

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Answer is d check my explanation above