Converting Ratios to Percents Video Lecture - Class 7

hello friends this video on comparing
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so now let's see how do we connect ratio
with percentages so now we know whatever
what is ratio now we also know what is
percentage so now we will try to see
that how we can link ratios with
percentages so in order to convert ratio
to person pages again we follow a few
very simple steps so let us look at this
example let's say that you have to
convert each part of this ratio 2 is to
3 is to 5 in two person dates so how
would you convert it into percentage so
the first step is that divide each part
by sum of all the parts so what are the
three parts here 2 3 & 5 these are the
three parts so what are the three parts
2 3 & 5 so we have to convert each of
these parts into a person things so I
mean it is something like this let us
say that the ratio of the ages of 3
people are 2 is to 3 is to 5 that means
if the it age of the first person is 2x
the age of the second person would be
creates and the age of the third person
would be 5x that is the meaning of 2 is
to 3 is to 5 so now if you have to
calculate or if you have to find out a
percentage of each of those people that
means that let's say if if you have to
express the same thing in terms of how
much percent of the total age is of the
first person how much percent of the
total age is of the second person or how
much percent of the total age is of the
third person so in that case you have to
convert each part into a percentage so
in order to do that what do you do you
convert you divide each parts the first
part is to divide it by some of the 3
parts that is 2 plus 3 plus 5 so you
divide 2 by 2 plus 3 but plus 5 and then
how do you soon in this way you get a
fraction
so 2 out of 10 6 X 5 plus 3 is 8 8 plus
2 is 10 so this is 2 out of 10 whose
total you have n and you are now
considering the first part which is 2 so
2 out of n and then you convert it into
percentage so you multiply by 100 and
put a person its symbol so in this way
you get it as 20 percent similarly for
the second part it into the same thing 3
divided by 2 plus 3 plus 5 which is 3
divided by 10 in 200 so this becomes 30
percent similarly 5 divided by 2 plus 3
plus 5 so this is 5 divided by 10 in 200
so this becomes 50 percent so you see
each part of the ratio got converted
into a percentage so if you see that the
chocolates have been divided amongst 3
friends in the ratio 2 is to 3 is to 5
so that means the first child got 20
percent of the chocolates the second
child got 30 percent of the chocolate
and the third child got 50 percent of
the chocolate so this is basically the
meaning of kind of version of the ratio
to percentages so let us look at this
real-life example so if the angles of a
triangle are in the ratio 2 is to 3 is
to 4 so which are the angles of the
triangle so these are the three angles
of the triangle they are in the ratio 2
is to 3 is to 4 what does that mean that
means that if we assume that let's say
the value of this angle is 2x then the
value of this angle would be 3x and the
value of this angle would be 4x why did
we consider X because we do not know
what is the real value of the angle if
the value could be anything
the real value could be 20 degree it
could be 40 degree it could be 100
degree it could be anything so we just
assumed that length there we have
it's such that if this value is 2x this
would be 3x and this would be 4x because
in that case the ratio will be 2 is to 3
is to 4 so you have to find out the
value of each angle now we already know
that sum of three angles of a triangle
is always equal to how much so we have
already learned this in our previous
lesson so the sum of the three angles is
always equal to 180 degrees so therefore
we can see that 2x plus 3x plus 4x is
equal to 180 degree
so 2 plus 3 plus 4 is 9 so 9 X is equal
to 180 degrees or we can say X is equal
to 180 degree divided by 9 so X will be
equal to 20 degree therefore what would
be the angles so the value of the angles
would be 2x that is 2 into 20 degree
which is 40 degrees 3x which is 3 into
20 degree which is 60 degree and 4 X
which is 4 into 20 that is 80 degree so
the three angles of the triangles would
be 40 degree 60 degree and eighty degree
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