120 (5×4!)
five multiplication & three addtion
Speed of train = 54km/hr
= 54 x (5/18) m/s
= 15 m/s
Length of train = 165m
Time required to cross a bridge of 660m in length = (660+165) / 15
= 55 seconds
₹1 today increases to (1+1/8) = 9/8 after 1year.
After 2 years it increases to 9/8 of 9/8 = (9/8)^2 =81/64 times.
Hence ₹64000 increase to 64000×81/64 =₹81000
This is more logical …
Let the 1st flag 1 placed at the origin ….
in crossing 8 flags he traveled 7 distances….
s=d/t
=7/8
time for 4 flags t=(d/s)=4/(7/8)=(4*8)/7=4.5714285714285714285714285714286
CORRECT ANS : B
167
23 Teams
Days taken by A to complete whole work= 140 days
Days taken by B to complete whole work= 105 days
A’s 1 day work= 1/140
B’s 1 day work= 1/105
On adding these together we get: 1/60 (1 day work by working together)
So, together they will be able to complete it in 60 days
let A goes up and B comes down.
assume A takes 1 step in 1sec.
hence,B takes 5 steps in 1sec.
50 steps ll be moved by A in 50/1=50secs
125 steps ll be moved by B in 125/5=25 secs
hence speed of escalator=(difference of no of
steps)/(difference of time)
speed=(125-50)/(50-25)= 3 steps/sec
hence during upward journey of 50secs by A,total steps=50 by
A and 150 by escalator..total=150+50=200
during downward journey of 25 secs by B,total steps=125 by B
and 75 by escalator..total=125+75=200steps.
ANS:200 steps
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.
35Kg
A