Question

Consider a road map of a city having 5 approach roads from other places, 10 junctions and no internal road has a dead-end. Every junction except one is associated with 4 roads. If n number of roads are associated with the remaining junction, then which of the following values is impossible for n?

Answer 1

pls can anyone give explanation

Answer 2

Given,

The city has 5 approach roads

10 junctions

no internal roads

1 dead end

Every junction, except 1 is associated with 4 roads

To find,

What is an impossible value for n

Solution,

The information given makes it clear that the maximum number of roads connected to any junction can be 5 and the minimum can be 0

9 out of 10 junctions is connected by 4 roads.

So, the number of roads which can be associated with the remaining junction ranges between 0 - 5

Thus, the value impossible for n is 6

Hence, 6 is the value impossible for n