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SSC CHSL 2022 PYQ — Question 60

SSC CHSL - 31 May 2022 - Shift 3 • Quantitative Aptitude • Q60

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Sunila drove her car at an average speed of 45 km/h for the first 75 km of a trip, and then at an average speed of 70 km/h for the remaining 45 km of the trip. If she made no stops during the trip, what was Sunila's average speed (in km/h) for the entire trip?

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 519397\frac{93}{97}.

Formula Used:

Average speed=total distancetotal timeAverage\ speed = {total\ distance \over total\ time}

Explanation:

According to the given question,

Time for first 75 km, T1 = 7545=53{75 \over 45} = {5 \over 3} hr.

Time for next 45 km, T2 = 4570=914{45 \over 70} = {9 \over 14}

Now, Average speed=(75+45)(53+914)Average\ speed = {(75 + 45) \over {({5 \over 3} + { 9 \over 14})}}

⇒Average speed=(120)9742Average\ speed = {(120) \over {97 \over 42}}

⇒Average speed=504097Average\ speed = {5040 \over 97}

⇒ Average speed = 51939751\frac{93}{97}

Hence the required answer is 51939751\frac{93}{97}.