SOLUTION: Please help me solve just two more questions PLease. Thank you. 1.Eight students are on standby to fly back to school at the end of spring break. The airline finds it has space

Question 1036011: Please help me solve just two more questions PLease. Thank you.
1.Eight students are on standby to fly back to school
at the end of spring break. The airline finds it has
space for three of them. How many ways can the
three be selected ignoring who were first to arrive
at the terminal?

2.An ATM keypad has ten keys. A PIN code is entered
by pressing a sequence of four keys.
(a) How many PIN codes are possible if no key is
pressed twice in a code?
(b) How many PIN codes are
possible if a key may be
pressed more than once in
a code?
(c) A bank changes the PIN
codes to a sequence of six
keys. Find the number of
PIN codes possible if a key
may be pressed more than
once in a sequence. Discuss the increase in security
by going to a six-key code.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
1.Eight students are on standby to fly back to school
at the end of spring break. The airline finds it has
space for three of them. How many ways can the
three be selected ignoring who were first to arrive
at the terminal?
-----
Ans: 8C3 = (8*7*6)/(1*2*3) = 8*7 = 56 ways
----------------------------
2.An ATM keypad has ten keys. A PIN code is entered
by pressing a sequence of four keys.
(a) How many PIN codes are possible if no key is
pressed twice in a code?
Ans: 10*9*8*7 = 5040
-------------------------------
(b) How many PIN codes are
possible if a key may be
pressed more than once in
a code?
Ans: 10^4 = 10000
----------------------
(c) A bank changes the PIN
codes to a sequence of six
keys. Find the number of
PIN codes possible if a key
may be pressed more than
once in a sequence. Discuss the increase in security
by going to a six-key code.
Ans: 10^6 = 1000000 ways
----
The 6 key code is 100 times more secure as the 4 key code.
Cheers,
Stan H.
--------------
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