Problem Set 1 : Boats and Streams, Quantitative Aptitude Video Lecture | Study Quantitative Aptitude for Competitive Examinations - Quant | Best Video for Quant

hello friends how are you welcome to the
team s channel and welcome to this video
so we are presenting you the second part
of the boards and Steve's so in this
video we'll try to solve some problems
so let's begin let's see the first
problem the speed of the bot in standing
water is 9 kilometres per hour and the
speed of the stream is 1.5 kilometers
per hour so a man grows to place at a
distance of 105 kilometers and he comes
back to the starting point so we have to
find the total time taken by him so now
we know that the speed of the upstream
is the speed of the boat in standing
order - the speed of the stream so it
will be 9 minus 1.5 which gives seven
kilometres per hour so now in order to
calculate the speed of the downstream we
all know that we'll just add the speed
of the boat in standing water to the
speed of the stream which is nine plus
1.5 which gives us 10.5 km/h next we
recreate the time taken upstream and the
time taken downstream by the boat so as
we know the distance is 1 into 5
kilometers and we know the speed of op C
and the speed of downstream so using the
time distance formula
well you calculate time is equal to
distance upon speed which gives us time
taken obscene equals to 105 divided by 7
equals 15 and in the case of downstream
we have 10 hours time so we will just
add these two times which gives us 25
hours the answer to this equation let's
see the next question in this problem we
are given that a man can draw 3/4 of a
kilometer so we know here the distance
is 750 meters
so we know that he can draw against the
stream in 10 minutes and down the stream
in 5 minutes so we need to calculate the
speed in kilometers per hour of the man
in Stillwater so this question is a bit
tricky because we got the values in in
meters and in minutes but we need to
specify our answer in kilometers per
hour so let's see how to do this first
of all we have the distance equals to
750 meters and we also know the time
upstream in the time downstream which is
six hundred and three hundred meters
seconds respectively
so we can calculate the speed of C and
the speed of the boat in downstream
which is 750 divided by 600 this gives
us five divided a 4 meter per second of
them for upstream and for downstream we
have 750 meters divided by 300 seconds
equals 2 5 divided by 2 meter per second
so now we have the speed of the boat in
upstream and the speed of the boat in
downstream next we can click rate the
speed of the boat in still water which
is speed of the boat in upstream the
speed of the boat in downstream divided
by 2 we all know how this formula came
from in the previous video so in order
to see how this formula came up you can
watch the previous video which is the
board system part 1 and next we get 15
by 8 meters per second so we know the
speed of the boat in still water in
meter per second but we need to convert
it into kilometers per hour so hope will
do is so in order to convert from meter
per second to kilometers per hour we
need to multiply it by 18 by 5 so we'll
just multiply 15 divided by 8 into 18 by
5 to get the answer in kilometers per
hour which is 54 divided by 8 or in
decimals we can say 6.75 lumens per hour
so that is it for this video guys so as
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