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
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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.
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