Science stream knowledge

 5 Most important question regarding permutations and combinations with deep concept.

1.A person want to travel from station P to R via Q.If there are 4 ways from P to Q and 5 ways from Q to R then find out the number of way this person can travel from P to R.

Solution: Given that there are 4 ways from station P to Q and 5 ways from Q to R.

A person want to travel from station P to R via Q.

So the number of way he travels = first P to Q and then second Q to R = 4×5 = 20

Hence the total number of ways = 20.

2.A person want to travel from station P to R via Q.If there are 7 ways from P to Q and 8 ways from Q to R then find out the number of way this person can travel from P to R.

Solution: Given that there are 7 ways from station P to Q and 8 ways from Q to R.

A person want to travel from station P to R via Q.

So the number of way he travels = first P to Q and then second Q to R = 7×8 = 56

Hence the total number of ways = 56.

3.A Lady want to travel from station P to R via Q.If there are 12 ways from P to Q and 9 ways from Q to R then find out the number of way this lady can travel from P to R.

Solution: Given that there are 12 ways from station P to Q and 9 ways from Q to R.

A lady want to travel from station P to R via Q.

So the number of way she travels = first P to Q and then second Q to R = 12×9 = 108

Hence the total number of ways = 108.

4.A person want to travel from station P to R via Q.If there are 4 ways from P to Q and 10 ways from Q to R then find out the number of way this person can travel from P to R.

Solution: Given that there are 4 ways from station P to Q and 10 ways from Q to R.

A person want to travel from station P to R via Q.

So the number of way he travels = first P to Q and then second Q to R = 4×10 = 40

Hence the total number of ways = 40.

5.A person want to travel from station P to R via Q.If there are 9 ways from P to Q and 15 ways from Q to R then find out the number of way this person can travel from P to R.

Solution: Given that there are 9 ways from station P to Q and 15 ways from Q to R.

A person want to travel from station P to R via Q.

So the number of way he travels = first P to Q and then second Q to R = 9×15 = 135

Hence the total number of ways = 135.

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