11. C
12. D
13. x = 1.35
14. A
There are 150 confident adults out of 1000.
Selecting four at random withOUT replacement
Probability that all four are confident
=(150/100*149/999*148/997*147/996)
=150!/146! / (1000!/996!)
= 7301/14925090
= 0.00048918
(check: answer < (150/1000)^4=0.00050625, ok)
10 digits
if you can repeat them, then there are 10^4 possibliities or 10000 combinations
A number multiplied by 10 will just have a zero added onto the end of it.
For example: 4x10=40
5x10=50
10x10=100
So, in this case 4,230 would be multiplied by 10 to get 42,300.
4,230x500= 2,115,000
