Question

In a survey of 100 people 72 reads physics , 62 reads biology and 52 reads chemistry, 22 read any two of them find number of people who reads all these three​

Answer 1

Answer:

32      Please make as brainliest

Step-by-step explanation:

Physics only (p)

Chemistry only (c)

Biology only (b)

Physics and Chemistry (pc)

Physics and Biology (pb)

Chemistry and Biology (cb)

All three (x).

So only one subject and all three and any two = 100

So only one subject and all three = 100 - 22 = 78

That is, x + p + c + b = 78 —eq1

Consider physics,

x + p + pc + pb = 72 —eq2

Consider Biology,

x + b + pb + cb = 62 —eq3

Consider Chemistry,

x + c + pc + cb = 52 —eq4

Any two,

pc + pb + cb = 22 —eq5

Add 2, 3 and 4.

3x + p + b + c + 2(pc+ pb + cb) = 186

Substitute 5,

3x + p+ b + c = 186 - 44 = 142 —eq6

eq6 - eq1

2x = 142 - 78 = 64

x = 32.