Examples: All Conversions related and word problems Video Lecture | Mathematics for Grade 7

hello friends this video on comparing
quantities part 12 is brought to you by
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we have learned a lot of things about
percentages let us try to solve some of
the questions now question number one
convert the given rational number in two
percent three by 40 so 3 by 40 is the
fractional numbers how do you convert it
into percentage you multiply the
numerator and the denominator by 100
now everything except the denominator
hundred is considered as one number so
you write it as three in 200 divided by
40 and this denominator hundred gets
represented by the person it's symbol so
this is becomes 2 into 22 into 50 so
this 0 0 cancels out so you get 15 by 2
percentage now 15 by 2 if you convert it
into decimals you get 7.5 percent
question number 2 convert the given
decimal fraction to percent that is 12
point three five so first of all let us
try to write this decimal number in
fractional form so this can be written
as 1 2 3 5 divided by 100 by 2 zeroes
because they are a two digits after the
decimal point so now we have a
fractional number so we will repeat the
same process we'll multiply the
numerator and the denominator by 100 so
we will consider all of these together
so this becomes 1 2 3 5 in 200 divided
by 100 percent
so hundred hundred will cancel out so
this would be equal to 1 2 3 5 percent
question number three estimate what part
of the figure is colored and hence find
the person which is colored so when you
look at this figure how many total parts
do you have how many total triangles do
you see in this figure so the total
number of part
that we see here is one two three four
five six seven and eight
so total parts is eight and how many
parts are colored so colored parts are
one two and three so three parts are
colored so can you tell with how what
fraction of the circle is colored so
fraction of the circle that is colored
so fraction means how much out of the
total parts of the circle is colored so
we will see three parts out of eight
parts so three by eight now we have to
represent so we have already estimated
what part of the figure is colored now
we have to find out the percentage which
is colored so how do we calculate
percentage all we need to do is we need
to convert this fraction into percentage
so for that we multiply the numerator
and the denominator by 100 so this
entire thing will come together that is
300 by eight percent so 300 by eight is
nothing but thirty seven point five
percent so this person 37 five point
five percent of the figure is colored
find twenty percent of rupees 2500 so
how do you find twenty percent of rupees
2500 so 20 percent is nothing but 20 out
of hundred of rupees 2500 that means x
rupees two thousand five hundred so 100
into 25 gives 25 hundred so this would
be five hundred so twenty percent of two
thousand five hundred would be rupees
500 question number five find the whole
quantity if 8 percent of it is for 40
liters so in this case also we do not
know how much is the whole quantity so
let us assume that the whole quantity is
X so let us say that the whole quantity
is X so as for the question eight
percent of
is 40 liters so we can say eight we can
say eight persons not empty so eight
percent of X is equal to 40 so this can
be written as 8 out of 100 into X is
equal to 40 or we can say X is equal to
40 in 200 divided by 8 so 8 files of 40
this is equal to 500 therefore the whole
quantity was 500 liters question number
6 out of 15,000 voters in a constituency
60 percent voted find the percentage of
voters who did not vote so how many
voted 60% that means if they assume that
the total number of voters is 100 then
60 out of them voted so what does that
mean how many not voted so how many not
vote it would be 100 minus 60 now we are
talking about the percentage only here
so if this doesn't mean that what voters
did not vote it means what a percent of
the voters did not vote because when is
a 60% we mean that if we assume that
there are total hundred voters then 60
of them voted so how many did not work
what they did not vote so if there are
total hundred voters then 40 of them did
not vote so 40 percent of the voters did
not vote can you now find how many
actually did not vote so can you find
the actual number so this is the number
only when you consider that the total
number of voter is hundred but the total
number of voters in reality is 15,000
therefore actual number of people who
did not vote so what would be the actual
number that actual number would be
nothing but what a percent of 15,000 so
this would be equal to forty by hundred
into fifteen thousand
so this would be equal to 6000 so 6000
people actually did not vote question
number 7 divide 15 Suites between Manu
and solo so that they gave 20% and 80%
of them respectively so you have to
divide it in such a way that Manu gets
20% of the total Suites that is 20% of
15 and so you should get 80% of total
number of suites that is 80% of 15 so
20% of 15 would be 20 by 100 into 15 so
this is going to be equal to 3 so one
who should be given 3 Suites
similarly 80 percent of 15 would be 80
by 100 into 15 so this would be 2 4 8 2
5 and 10 Forza 4 3 10000 55 3 is a 15 so
this would be 12 so shown you should get
12 3 so 3 sweets to manu and 12 sweets
to solo
now if I ask you to find out the ratio
of the sweets given to solo and Manu
that would be 3 by 12 which is 3 is to
12 which can be written as 1 is to 4
because 1 is to 4 and 3 is to 12 these
are equivalent ratios so the ratio of
the number of sweets that Manu and
swollen who has is 1 is to 4 thank you
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