Model 3 Problems on average speed Section-Wise Topic Notes With Detailed Explanation And Example Questions
MOST IMPORTANT quantitative aptitude - 5 EXERCISES
The following question based on time & distance topic of quantitative aptitude
(a) 31 km/hr
(b) 29 km/hr
(c) 30 km/hr
(d) 23 km/hr
The correct answers to the above question in:
Answer: (c)
Using Rule 2,If a man travels different distances $d_1,d_2,d_3$,... and so on in different time $t_1,t_2,t_3$ respectively then,Average speed= $\text"total travelled distance"/\text"total time taken in travelling distance"$= ${d_1 + d_2 + d_3 +...}/{t_1 + t_2 + t_3 +...}$
Distance covered
= $(35 × 10/60 + 20 × 5/60)$ km
= $(35/6 + 10/6) = 45/6$ km
Total time = 15 minutes
= $1/4$ hour
Required average speed
= $\text"Distance covered"/ \text"Time taken"$
= $45/6 × 4$ = 30 kmph
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Read more problems on average speed Based Quantitative Aptitude Questions and Answers
Question : 1
A man goes from A to B at a uniform speed of 12 kmph and returns with a uniform speed of 4 kmph His average speed (in kmph) for the whole journey is :
a) 6
b) 4.5
c) 8
d) 7.5
Answer »Answer: (a)
Using Rule 5,
If two equal distances are covered at two unequal speed of x kmph and y kmph,
then average speed = $({2xy}/{x + y})$
= ${2 × 12 × 4}/{12 + 4} = 96/16$ = 6 kmph
Question : 2
A car completed a journey of 400 km in 12$1/2$ hrs. The first $3/4$th of the journey was done at 30 km/hr. Calculate the speed for the rest of the journey.
a) 40 km/hr
b) 30 km/hr
c) 45 km/hr
d) 25 km/hr
Answer »Answer: (a)
Total distance covered = 400 km.
Total time = $25/2$ hours
$3/4$th of total journey
= $3/4$ × 400 = 300 km.
Time taken = $\text"Distance"/ \text"Speed"$
= $300/30$ = 10 hours
Remaining time = $25/2$ –10
= ${25 - 20}/2 = 5/2$ hours
Remaining distance = 100 km.
∴ Required speed of car
= $100/{5/2} = {100 × 2}/5$ = 40 kmph.
Question : 3
A man goes from a place A to B at a speed of 12 km/hr and returns from B to A at a speed of 18 km/hr. The average speed for the whole journey is
a) 15$1/2$ km/hr
b) 16 km/hr
c) 14$2/5$ km/hr
d) 15 km/hr
Answer »Answer: (c)
Using Rule 5,
Average speed
= $({2xy}/{x + y})$ kmph
= $({2 × 12 × 18}/{12 + 18})$ kmph
= $({2 × 12 × 18}/30)$ kmph
= 14$2/5$ kmph
Question : 4
With an average speed of 40 km/ hr, a train reaches its destination in time. If it goes with an average speed of 35 km/hr, it is late by 15 minutes. The total journey is
a) 70 km
b) 80 km
c) 30 km
d) 40 km
Answer »Answer: (a)
Let the length of journey be x km, then
$x/35 - x/40 = 15/60 = 1/4$
${8x - 7x}/280 = 1/4$
$x = 280/4 = 70$ km
Question : 5
Gautam goes to office at a speed of 12 kmph and returns home at 10 kmph. His average speed is :
a) 10.9 kmph
b) 12.5 kmph
c) 11 kmph
d) 22 kmph
Answer »Answer: (a)
Here distances are same.
∴ Average speed = $({2xy}/{x + y})$ kmph
= $({2 × 12 × 10}/{12 + 10})$ kmph
= $(240/22)$ kmph = 10.9 kmph
Question : 6
A train travels 500 m in first minute. In the next 4 minutes, it travels in each minute 125 m more than that in the previous minute. The average speed per hour of the train during those 5 minutes will be
a) 50 km/hr
b) 55 km/hr
c) 30 km/hr
d) 45 km/hr
Answer »Answer: (d)
Using Rule 2,If a man travels different distances $d_1,d_2,d_3$,... and so on in different time $t_1,t_2,t_3$ respectively then,Average speed= $\text"total travelled distance"/\text"total time taken in travelling distance"$= ${d_1 + d_2 + d_3 +...}/{t_1 + t_2 + t_3 +...}$
Total distance covered by train in 5 minutes
= (500 + 625 + 750 + 875 + 1000) metre
= 3750 metre = 3.75 km.
Time = 5 minutes
= $5/60$ hour = $1/12$ hour
Speed of train = Distance Time
= $(3.75/{1/12})$ kmph
= (3.75 × 12) kmph = 45 kmph
GET time & distance PRACTICE TEST EXERCISES
Model 1 Basic Time & Distance using formula
Model 2 Vehicles in x/y of its usual speed
Model 3 Problems on average speed
Model 4 Time & Distance with Ratios
Model 5 Problems with Races
time & distance Shortcuts and Techniques with Examples
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Model 1 Basic Time & Distance using formula
Defination & Shortcuts … -
Model 2 Vehicles in x/y of its usual speed
Defination & Shortcuts … -
Model 3 Problems on average speed
Defination & Shortcuts … -
Model 4 Time & Distance with Ratios
Defination & Shortcuts … -
Model 5 Problems with Races
Defination & Shortcuts …
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