Maths Simple Equation part 11 (Questions: Application of Equation) CBSE Class 7 Mathematics VII Video Lecture | Extra Documents & Videos for Class 7

hello friends this video on simple
equations part 11 is brought to you by
exam feel calm no more fear from exam so
now let us again look at some of the
questions based on the applications of
simple equations question number one
Maya Medora and Messina I friends
studying in the same class in a class
test in geography Maya got 16 out of 25
Madrid were 20 their average score was
19
how much did was in our score so in this
question whose score is something that
we do not know we know that Maya's code
16 we also know Madras code 20 what
about Messina we do not know more
sinners code so let us assume that
Mussina's code is X right now what is
the condition that is given in the
question the condition is that the
average of their soul is given as 19 now
considering maecenas chorus X mile
school is 16 and mathura score is 20 how
do we find the average of their scores
we have learned how to find average in
the previous lesson on the right the
average is about summing them up divided
by they're numbered so how what are this
what would be the sum X plus 16 plus 20
divided by how many of them are present
three Maya Madeira and Messina so this
divided by three but according to the
question this average is actually 19 so
that means x plus 16 plus 20 divided by
3 is equal to 19 so this is our equation
so how do we solve this 6 plus 20 plus
16 is 36 divided by 3 is equal to 19 now
let's move 3 to the right hand side so
we get X plus 36 is equal to 19 into 3
so 19 into 3 is 57 so X plus 36 is equal
to 57 or we can say X is
- 57 - 36 which is equal to 21
therefore Muslim asshole is 21 out of 25
question number two people of sundaram
planted a total of 102 trees in the
village garden some of the trees were
fruit trees the number of non fruit
trees went to more than three times the
number of fruit trees what was the
number of fruit trees now we need to
find the number of fruit trees so let us
assume that the number of fruit trees is
X that is enemy's our first step is to
assume something that we do not know as
X now let's make use of the condition
that is given the condition is number of
non fruit trees is to more than three
times the number of fruit trees so three
times the number of fruit trees plus two
more
that is three X plus two this is going
to be the number of non fruit trees now
according to the question the total
number of trees that was planted was
hundred two so total number of trees
would be fruit plus non fruit trees the
sum of these two is equal to hundred two
now fruit trees is X non fruit trees is
three X plus two so basically X plus 3 X
plus 2 is equal to 102 so X plus three X
would be 4 X plus 2 is equal to 102 so
let's solve this to find out the value
of x so 4 X will be equal to 102 minus 2
or we can say 4 X is equal to hundred
therefore X is equal to hundred divided
by 4 so we know that 4 into 25 is 100
therefore X is equal to 25 and what was
X X was the number of fruit trees so the
number of fruit trees planted is 25
question of the tree even he thinks of a
number if she adds 19 to it and divides
the
by five she will get eight so you have
to definitely find that number so let us
say that let the number be X now she
adds 19 to that number that means X plus
19 and then she divides this sum by five
that means X plus 19 divided by five and
what does she get she gets the result as
eight so this is a pretty simple
equation and we can definitely solve
this so this becomes X plus nineteen we
move five to right-hand side so it
becomes 8 into 5 so X plus 19 is equal
to 8 into 5 that is 40 so we can say X
is equal to 40 minus 19 therefore X is
equal to 21 so 21 is the number that she
thought of question number 4 if I take
3/4 of a number and count up three more
I get 21 what is the number same pretty
simple let us say that the number is X
so what are we actually doing
we take 3/4 of this number that means 3
by 4 X and then we count up three more
that means we are adding three more to
it so 3 by 4 X plus 3 and what do we get
we get 21 so 3 by 4 X plus 3 is equal to
21 this is our equation and we have to
find X so let us first move this 3 to
right-hand side so keep it 21 minus 3 so
we can say 3 by 4 X is equal to 18 or
this 4 can move this side so this
becomes 3 X is equal to 18 into 4 or we
can say 3 X is equal to 18 into 4 is 72
or X is equal to 72 divided by 3 so 3 to
the 6 3 4 12 so X is equal to 24 so the
number is 24 so with this we have
reached towards the end of this lesson
and I am very
sure that you would have felt that this
lesson on simple equations was very very
interesting and simple as well as the
name said simple equations the equations
but it is simple to do soil and to make
them so trying to solve more and more
questions this is a very interesting
lesson if you try solving it yourself it
you know it's really good you are really
going to be very very good at it so read
the question understand it set up an
equation following the tips that I gave
you and then solve the equations very
simply using the four tips that I had
mentioned so I hope this lesson would
have helped choose you all in the next
lesson
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