The solution to the above question is B: 12.5%

This question seems hard at the first glance, but making a Venn Diagram makes it easy to understand.

Attachment:

Speeding Ticket.PNG [ 8.25 KiB | Viewed 493 times ]
Notation:

M represents the set of all motorists

S represents the set of motorists who exceeded speed

T represents the set of motorists who exceeded speed and got a ticket

The question says that 20% of all motorists who exceeded speed did not get a ticket.

Have a look at the Venn Diagram. Which area represents such motorists?

The orange one.

So, if orange area is 20% of the set S, then what % of S will be the red area?

80%.

It's also given that 10% of all motorists exceed speed and get a ticket. Which area of the diagram represents these motorists?

Again, the red area.

So, we get the equation:

10% of M = 80% of S

So, S = 1/8 of M = 12.5% of M.

Hence, Option B.

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