00:01
In lee middle school, the ratio of number of fifth graders to number of 60 graders is 4 to 3.
00:09
Suppose, let us try to write the given data.
00:14
Suppose let us assume number of fifth graders.
00:21
Number of fifth graders equal to x5.
00:24
Let us take like this, okay? and number of sixth graders, okay, number of sixth graders equal to x6.
00:33
And similarly, there are also seventh graders.
00:37
So number of seventh graders equal to x7.
00:43
Suppose let us take these numbers, okay, because we didn't know the values.
00:50
Now, from the given data, we can write, from the given data, we can write.
00:57
The ratio of number of 50 graders and number of 60 graders is 4 to 3.
01:04
So it is given that x5 by x6 equal to 4 by 3 because this is the ratio.
01:12
So this is the first one we have given.
01:15
And now, and there are 15 more 50 graders.
01:19
Okay, it is given that 50 graders are 15 more than 60 graders.
01:26
Okay, so x5 equal to x6 plus 15.
01:30
So this is the 2 we have given.
01:32
And next one is ratio of number of of 6th graders to number of 7th graders.
01:37
That means x 6x7 equal to 3 by 4.
01:42
This is the third one we have given.
01:45
Now we are asked to find what is the mean number of students.
01:48
We are asked to find the mean of all these 3...