Please refer to the graph regarding the relation between spee

Question

GMATBusters’ Quant Quiz Question -3 https://gmatclub.com/forum/download/file.php?id=52964 Please refer to the graph regarding the relation between speed and distance for a journey undertaken by Bob. The average speed (km/hr) for the first 150 km is: A 12 B 20.5 C 22.5 D 25 E None of the above Quiz 3.JPG

pk123 · Answer

Average speed=150/(100/20)+(50/30)
=150/(5+5/3)
=150×3/20
=45/2
=22.5

C is the answer

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shameekv1989 · Answer

Please refer to the graph regarding the relation between speed and distance for a journey undertaken by Bob. The average speed (km/hr) for the first 150 km is:
A 12
B 20.5
C 22.5
D 25
E None of the above

For the first 100 kms Rate is 20 kmph -> Time taken for first 100 kms is 5 hrs

For the next 50 kms Rate is 30 kmph -> Time taken for next 50 kms is  \frac{5}{3}  hrs

Average for 150 kms is 
 \frac{150}{(5+  5/3} )   = 22.5 hrs -> Answer - C

KhulanE · Answer

Total time to travel 150miles 100/20+50/30=6.66
Average speed 150/6.66=22.5
so C is right

Raxit85 · Answer

Please refer to the graph regarding the relation between speed and distance for a journey undertaken by Bob. The average speed (km/hr) for the first 150 km is:
A 12
B 20.5
C 22.5
D 25
E None of the above

0 to 100 km, t1 = 100/20 = 5
100 to 150 km, t2 = 50/30 = 1.66

Average speed = total distance/total time = 150 / 6.66 = 22.5

So, C is correct.

ajaymahadev · Answer

The equation for average speed is (total distance)/(total time)

globaldesi · Answer

time taken for first 100 km =  \frac{100}{20 } = 5hrs
time taken to cover next 50 km =  \frac{50}{30} = \frac{5}{3}  hrs
avg speed 
total distance /total time
=  \frac{150}{(5+5/3)} 
 \frac{45}{2} 
= 22.5
C

shridhar786 · Answer

total distance = 150 km

bob covered first 100 km with speed = 20 km/hr
time taken to cover 100 km =  \frac{100}{20 } = 5 hours

bob covered next 50 km with speed = 30 km/hr
time taken to cover next 50 km =  \frac{50}{30}  = 5/3

time taken to cover 150 km =  \frac{20}{3}  hours

average speed =  \frac{total-distance-covered}{total-time-taken}  =  \frac{150}{20/3 }  =  \frac{45}{2}  = 22.5

C is the answer

newyork2012 · Answer

T= 100/20 + 50/30 = 20/3 
S=150
V=s/t = 450/20=22.5

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QuantMadeEasy · Answer

Average speed = total distance / total time

total distance = 150

total time time = time to cover (100km with speed of 20kmph + 50km with 30kmph)
 = 5+ (5/3)

Average speed = 150/(5+ (5/3)) = 90/4 = 22.5kmph

aditibarjatya · Answer

Solution :

Question 3 :  Please refer to the graph regarding the relation between speed and distance for a journey undertaken by Bob. The average speed (km/hr) for the first 150 km is:

A 12 
 B 20.5 
 C 22.5 
 D 25 
 E None of the above

In this question, we need to find the average speed for first 150 km shown on X-axis. The formula for average speed is \frac{{Total distance} }{ {Total time}}.

Here, total distance = 150 Km and total time can be calculated by considering the two intervals i.e., distance of 100 km at speed of 20 Km/hour and interval of 100-150 km at speed of 30 Km/hour. Thus, total time =  \frac{100}{20} + \frac{50}{30}    =  5 + \frac{5}{3}  =  \frac{20}{3}

Therefore, Average speed =  \frac{150 }{ (20/3)}  = 22.5 Km/hour, which is option C.

Option C  is the correct answer.

bM22 · Answer

Solution:

Let's see: Avg speed for a particular distance is :  total distance/total time taken .

So lets break the speed to required times till 150 kms is completed.

speed during the 1st 50kms = 20km/hr, so time taken : 5/2
speed during the next 50kms = 20km/hr, so time taken : 5/2
speed during the last 50kms= 30km/hr, so time taken is : 5/3

so total time taken: 20/3hr.

So the avg speed for the 1st 150 kms will be : 150/(20/3) = 22.5km/hr

Please refer to the graph regarding the relation between spee

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Please refer to the graph regarding the relation between spee

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