Question

69. If 30% pages of a book were read on Monday. 5 pages were read
on Tuesday. then 72 pages were left to be read. How many pages
does the book have ?
(1) 480
(2) 360
(3) 200
(4) 240​

Answer 1

Question:

If 30% pages of a book were read on Monday. 50% pages were read on Tuesday. Then 72 pages were left to be read. How many pages does the book have ?

(1) 480

(2) 360

(3) 200

(4) 240

Answer:

(2) 360

Solution:

Let the total number of pages in the book be x .

Then ,

No. of pages read on Monday = 30% of x

No. of pages read on Tuesday = 50% of x

No. of pages left to be read = 72

Now,

=> Total no. of pages in the book = No. of pages read on Monday + No. of pages read on Tuesday + No. of pages lest to be read .

=> x = (30% of x) + (50% of x) + 72

=> x = (30/100)•x + (50/100)•x + 72

=> x = (3/10)•x + (5/10)•x + 72

=> x = 3x/10 + 5x/10 + 72

=> x = (3x + 5x)/10 + 72

=> x = 8x/10 + 72

=> x - 8x/10 = 72

=> (10x - 8x)/10 = 72

=> 2x/10 = 72

=> x/5 = 72

=> x = 72•5

=> x = 360

Hence,

The total number of pages in the book is 360 .

Answer 2

Question:-

If 30% pages of a book were read on Monday.50% pages were read on Tuesday.Then 72 pages were left to be read.How many pages does the book have?

1)480

2)360

3)200

4)240

____________________

$\huge\underline\mathfrak{Answer\::}$

Number of pages =2) 360

_________________________

Let the number of pages = N

According to question now:-

N = N × 30% + 50% of N + 72

=> N =N × 30/100 +N × 50/100 + 72

=> N = 3N/10 + N/2 + 72

=> N = (3N + 5N + 720)/10

=> 10N = 8N + 720

=> 10N -8N = 720

=> 2N = 720

=> N = 720/2

=> N = 360

_______________________

Verification:-

360 = 360 × 30% + 360×50% + 72

=> 360 = 108 + 180 + 72

=> 360 = 360 [Hence proved]

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