Question

the ratio of the number of maths book to that of other book is 4:7 and the total number of other books is 1050.Howmany mathematics books are purchased so that the ratio of the number of mathematics books to that of other books will be 3:5?​

Answer 1

Answer:

300

Step-by-step explanation:

let common factor is x

so 7x=other books

4x=math books

7x=1050

so x=1050/7=150

so math books=150x4=6000

let in the last ratio ie;3:5

common factor=y

math books=3y

other books=5y

we know that we have to purchase some math books but not other books so 5y=1050

y=210

3y=6300

6300 is the number of books after the purchase

the books we had earlier=6000

6300-6000=300

so 300 new books have to be purchased.

hope it helps

Answer 2

Answer:

30

Step-by-step explanation:

Let the original no. of maths books and other books be 4x and 7x.

7x=1050

x=150.

No. of maths books = 4*150=600.

Total no. of books=600+1050=1650.

Let the total no. of maths books after purchasing be 3y; and 7x=5y

5y= 1050

y=210.

3y=210*3=630.

No. of maths books purchased= Total no. of maths books after purchasing- original no. of maths books

=630-600=30