12. A train 210 m long takes 12 seconds to pass a 90 m long tunnel. Find the speed of the train in km/hr
13. Anuj is driving his car at a constant speed of 45 km/hr
(a) How far will he reach in 220 minutes?
(b) In how much time will he cover a distance of 180 km?
14. Brass is made from zinc and copper Sohan mixed 6 kg of zinc with 9 kg of copper How much zinc
does Sohan need to mix with 30 kg of copper?
15. Shall cycles to her school at an average speed of 12 km/hr. It takes her 20 minutes to reach the
school. What should be speed is she wants to reach her school in 15 minutes?
16.600 soldiers in a fort had enough food for 30 days. After 6 days, some soldiers were sent to another
Fort and thus the food lasted a total of 40 days. How many soldiers left for the Fort?
17. A train 250 m long is running at 80 km/hr. How much time will it take to cross a platform 150 m long?
Answers
Answer:
Step-by-step explanation:
length of the train =210 m
time taken to cross the 90 m tunnel =12 second
the speed of the train =distance /time
=90m + 210 m/0.2 minute
=300m/ 0.2minute
=1500 m/minute
=90 km/h
45 km/hr = 45000/60*60 = 12.5 m/s
220 minutes = 220*60 = 13200 seconds
Distance = speed * time
= 12.5*13200
= 165000 m
6kg zinc+9 kg copper
So ratio of zinc to copper=6/9=2/3
For 30 kg copper he requires=30×2/3=20kg
30-6=24
24 men had enough food for
600 soldiers
1 man had enough food for(600*24) soldiers
40 men had enough food for 600*24/40=360 soldiers
remaining soldiers=600-360=240 --answer
Answer:
Heya mate.... .
❤❤❤
Here's ur answer :
12.»» To pass the tunnel completely the train has to travel a distance of 300m
so,
distance (d) = 300m
time (t) = 12s
speed (v) = d/t = 300/12
.°. speed (v) = 25 m/s
13. Given that, speed (v) = 45 km/h
(a) t = 220 min = 3.67 hr
distance (d) = ?
.•. d = v*t = 45*3.67 = 165.15 km
(b) distance (d) = 180 km
t = ?
.°. » t = d/v = 180/45 = 4 hr
14. 20 kg zinc
15. Here, speed = v, time = t
Given : v1 = 12 km/h , t1 = 20 min = 0.33hr
v2 = ? , t2 = 15 min = 0.25 hr
since, v1 = t1
v2 = t2
.°. v2 = t2 * v1/t1
» v2 = 0.25*12/0.33 = 9.09 km/hr
16. »« 30-6 = 24
24 men had enough food for 600 soldiers
1 man had enough food for (600*24) soldiers
40 men had enough food for 600*24/40
= 360 soldiers
Remaining soldiers = 600-360 = 240 soldiers
17.The total distance traveled by the train to cross platform =250+150=400m
distance (d) = 400m = 0.4 km
speed (v) = 80 km/h
time (t) = ?
we have,
»« time (t) = distance (d)/speed (v)
.°. »« t = 0.4/80 = 0.005 hrs.
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