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Joined: 20 Feb 2017
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GPA: 3.39
Re: Out of 300 vehicle-riders surveyed on a highway, 50% had a valid
[#permalink]
08 Sep 2026, 10:32
Solution
There are 300 riders.
Find the number in each category
Registration: (50%) of 300 = 150
Insurance: (40%) of 300 = 120
Emissions: (30%) of 300 = 90
All three: (4%) of 300 = 12
None: (10%) of 300 = 30
Therefore, the number with at least one document is:
\(300-30=270\)
Find the total of the pairwise overlaps
\(R+I+E-(RI+RE+IE)+RIE=270\)
Substitute:
\(150+120+90-(RI+18+IE)+12=270\)
\(372-(RI+IE+18)=270\)
\(RI+IE=84\)
We are told:
\(RI=2IE\)
So:
\(2IE+IE=84
IE=28\)
and therefore:
\(RI=56\)
Find riders with only registration
Start with all 150 registration holders.
Subtract those who also have insurance (56), and subtract those who also have emissions (18). But the 12 riders with all three were subtracted twice, so add them back once:
\(150-56-18+12 ={88}\)
Answer: C