the 3rd answer should be the correct one
Answer:
5 different numbers, 2 even
Step-by-step explanation:
Since we have 5 digits and they are non repeating we can use the permutation formula:

It gives us the amount of ways to arrange k objects out of n objects without repetition, but order does matter.
In our case the amount of 4 digit numbers that can be formed using the digits from 1 to 5 is: 
And out of those 5, only 2 are even
The percentage of reduction is 17%
<u>Explanation:</u>
Original price = $21
Reduced price = $17.43
Percentage of reduction = ?
Difference in price = $21 - $17.43
= $3.57
Percentage of reduction = 

Therefore, percentage of reduction is 17%
Answer:
1) 9 min 36 sec (9.6min)
2) 15 cm
Step-by-step explanation:
10 cm -->4 min
1 cm --> 0.4 min
24cm --> 9.6 min
15 cm--> 6min