there are 5 different roads from city a to city b.Three different roads from b to c and four different road that go directly from a to c.how many ways are there from a to c altogether
Answers
Answer:
If there are four roads from city A to city B, three roads from city B to city C, and two roads from city C to city D, how many ways are there to go and come back from A to D via B and C if a road cannot be used more than once?
Initially from A to D through B and C
We have = 4 x 3 x 2 = 24 ways
While returning from D to A through B and C we cannot choose the previous paths
So from D to C instead of 2 ways we have one
From C to B instead of 3 ways we have 2
And from B to A instead of 4 we have 3 ways
So number of ways we have from D to A will be = (4–1) x (3–1) x (2–1) = 3x2x1 = 6
Now total round trip ways become = 24 x 6 = 144
Taking example of above image we have
From A to D the following ways
aeh, aei, afh, afi, agh, agi
beh, bei, bfh, bfi, bgh, bgi
ceh, cei, cfh, cfi, cgh, cgi
deh, dei, dfh, dfi, dgh, dgi. (24)
Now suppose we t
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There are 4 cities situated at the end points of a square with sides of 10km. What is the minimum length of the road such that we can go from one city to another?
The answer is 144! .
When you are going to C to D there are 2 ways.
B to C 3 ways then
There are 3 ways
So you can use 3*2= 6
Ways to go B to D
Like wise that you can use 4*3*2= 24
Ways.
4! = 24
Then returning
There are 3 ways you can use B to A
2 ways C to B
One way D to C
Then back you can use 3*2*1 = 6 = 3!
So all you can use 24*6 = 144 ways.