12/05/2020
Examples 3
In a survey it was found that 8.%people like oranges ,85% like mangoes and 75% like both But 45 people like none of themDrawing Venn –diagram , find the number of the people whowere in the survey.
Soln:
Let O and M be the number of people who like oranges and mangoes respectively.
n (U) =n(OUM) + n(OUM)c
100%=n (O) + n (M) - n(O∩M) + n(OUM)c
100% =80% + 85% - 75% + n(OUM)c
n(OUM)c= 10%
According to the question,
10%of total number(say x)= 45
Or, x=4500/10 = 450