Question

20% of the seventh grade students have math class in the morning. 16 2/3% of those students also have science class in the morning. If 30 seventh grade students have math class in the morning but not science class, find how many seventh grade students there are.

Answer 1

Answer:

180

Step-by-step explanation:

first find the number of seventh grade students that have math in the morning

16 2/3% of seventh grade students that have math in the morning also have science in the morning

% that do not also have math science in the morning = 100 - 16 2/3

=83 1/3%

say no. of seventh grade students that have math in the morning = x

then 83 1/3% of x = 30

(83 1/3)/100 × x = 30

5x/6 = 30

5x=30 x 6

5x=180

x=180/5

x=36

so 36 seventh grade students have math in the morning

20% of all seventh grade students have math in the morning

let the number of seventh grade students be y

20/100 x p = 36

2p/10=36

p/5=36

p=36 x 5

p=180

Answer 2

Answer:

Hey Hi

Good Morning

I've solved this by an easy Venn Diagram where first Set is for Maths and second is for Science

Here total 7th graders are 180

Here (16.67% = 1/6 of 20%) are both maths and science and if 30 are maths but not science which is 5/6 of the 20% then by unitary method

If 5/6 = 30

then 1 = 36

If this 36 is actually 20% of 7th graders

then 100% = 36 x 5 = 180

Thus there are total 180 7th graders

Hope this helps

For any doubt comment below

Regards

Rishabh Bansal