Ramji sir
Length of train = 125Mtrs
Speed of man = 5Km/Hr
=(5*1000)/(1*3600)
=1.4M/s
Time taken for train to pass = 10s
Spd = D/T
Total Distance (Man distance+ Train Length)
#Distance covered by Man in 10s
D=Spd*T
= (1.4M/s*10s)
= 14Mtrs
#Train length = 125Mtrs
Total D = 14Mtrs + 125Mtrs
= 139Mtrs
Time taken = 10s
Sp = D/t
=139M/10s
=13.9M/s
A. Rs. 410
total sum = 205 Rs.
the answer is 45 km/h
Define x:
Let the total distance be x.
Find the time needed in terms of x for speed at 30 km/h:
Find the time needed in term of x for 40 km./h:
Find the difference in time:
Solve x:
Find the total time needed to for the whole journey:
Given that he was 40 mins late:
Find the minimum speed needed:
Answer: The minimum speed is 45 km/h
1920
12.9
2+3+5+7+11+13+17+19+23+29=129
129/10=12.9
444km
Since the speed diff is 5km/h
It takes 12 hrs to cover 60 extra kms
Therefore in 12 hrs the total dist covered is
Relative speed×time=(21+16)×12=444 kms
The last person covered 120.71 meters.
It is given that the platoon and the last person moved with
uniform speed. Also, they both moved for the identical
amount of time. Hence, the ratio of the distance they
covered – while person moving forward and backword – are
equal.
Let’s assume that when the last person reached the first
person, the platoon moved X meters forward.
Thus, while moving forward the last person moved (50+X)
meters whereas the platoon moved X meters.
Similarly, while moving back the last person moved [50-(50-
X)] X meters whereas the platoon moved (50-X) meters.
Now, as the ratios are equal,
(50+X)/X = X/(50-X)
(50+X)*(50-X) = X*X
Solving, X=35.355 meters
Thus, total distance covered by the last person
= (50+X) + X
= 2*X + 50
= 2*(35.355) + 50
= 120.71 meters
Note that at first glance, one might think that the total
distance covered by the last person is 100 meters, as he
ran the total lenght of the platoon (50 meters) twice.
TRUE, but that’s the relative distance covered by the last
person i.e. assuming that the platoon is stationary.
each pencil 100/25 = 4
each book 100/15 = 6.66
100 – 15 = 85
85-5*4 = 65
65/6.66 = 9
he can buy 9 books that is not in given options currently so
answer is NONE
64, 71, 80, 91, 104, 119, 135, 155
135 is wrong because from starting difference between 7 after that 9 after 11 ,13,17 and so on
10 x 27=270