RRB Group D 15-Sep-2018 Shift 1 Solved Paper

Question : 35 of 100

Marks: +1, -0

From a cloth store, 15 customers bought orange dress, 15 bought red dress, 20 bought blue dress, 2 bought all the three colours and 8 bought at least two of these. How many bought at least one dress from the store?

Validate

Solution:

The shaded portion represent customers who bought atleast two dresses.

\Rightarrow

Customers who bought exactly 2 dresses

=8-(2 × 2)=8-4=4

Thus we have,

{n}( {O})=15, {n}( {R})=15, {n}( {B})=20

{n}( {O} ∩ {R} ∩ {B})=2

{n}( {O} ∩ {R})= {n}( {R} ∩ {B})= {n}( {B} ∩ {O})=4

∴ {n}( {O} ∪ {R} ∪ {B})= {n}( {O })+ {n}( {R})+ {n}( {B})

- {n}( {O} ∩ {R})- {n}( {R} ∩ {B})- {n}( {B} ∩ {O})

\;\; + {n}( {O} ∩ {R} ∩ {B})

=15+15+20-4-4-4+2

=50-10=40

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