Question

Geeta read $\dfrac{3}{8}$ of a book on one day and $\dfrac{4}{5}$ of the remaining on another day. Find the portion of the book left unread after two days.
${\text{A}}{\text{.}}$$\dfrac{5}{4}$
${\text{B}}{\text{.}}$$\dfrac{1}{4}$
${\text{C}}{\text{.}}$$\dfrac{1}{8}$
${\text{D}}{\text{.}}$$\dfrac{5}{8}$

Answer 1

Hint: In this question Portion of the book left unread after two days $ = 1 - $(portion of the book read on one day + portion of the book read on another day)

Complete step-by-step answer:

Portion of the book left unread after one day $ = 1 - $portion of the book read on one day
$
   = 1 - \dfrac{3}{8} \\
   = \dfrac{{8 - 3}}{8} \\
   = \dfrac{5}{8} \\
$

Portion of the book read on another day$ = \dfrac{4}{5}$of the portion of the book left unread after one day
$
   = \dfrac{4}{5} \times \dfrac{5}{8} \\
   = \dfrac{1}{2} \\
 $

Portion of the book left unread after two days
$ = 1 - $(portion of the book read on one day + portion of the book read on another day)
$
   = 1 - \left( {\dfrac{3}{8} + \dfrac{1}{2}} \right) \\
   = 1 - \dfrac{7}{8} \\
   = \dfrac{1}{8} \\
$

Hence required value is $\dfrac{1}{8}$

So, option C is the correct answer.

Note: This type of word problem including fractions are first converted into mathematical equation according to the parameters given in question, like first we found the portion of the book left unread after one day then we found the portion of the book read on another day and finally got the value of the portion of the book left unread after two days solving the equations.