Statistic Problem

1. Known the number of ball n(s) = 100
Ask: The change take a ball with number divisible by 5 but not divisible by 3 if taken randomly.

Answer: For example A = ball with number divisible by 5 but not divisible by 3 n(A) = 14, namely 5, 10, 20, 25, 35, 40, 50, 55, 65, 70, 80, 85, 95 and 100

P(A) = n(A)/n(s) = 14/100 = 7/50

2. Known: One badminton team consist of 5 members, will decide 2 people play a single players, and 2 pairs to play double.

Ask: How many option can be made.

First Way Solution:
For example 5 people of badminton team are A, B, C, D, and E. Then we choose A and B to play single.

OptionSingleDouble
1
A, BCD, AE
2
A, BCE, AD
3
A, B DE, AC
4
A, BCD, BE
5
A, BCE, BD
6
A, BDE, BC

The option number when A and B choose as single player are 6 option. The way to choose player as single player are 10, namely AB, AC, AD, AE, BC, BD, BE, CD, CE, and DE.

From one option of single player will make 6 option so for all way to choose single player will get 10 x 6 = 60 option.

Second way solution:
• The number option to choose 2 people as single player use the following formula:
C25 = 5!/(2!(5-2)!) = 5!/(2!.3!) = 10

• The number option to choose first pairs to play double
C23 = 3!/(2!(3-2)!) = 3!/(2!.1!) = 3

• The number option to choose second pairs to play double
C12 = 2!/(1!(2-1)!) = 2!/(1!.1!) = 2

So the number all option can be made are 10 x 3 x 2 = 60

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