Answer with Step-by-step explanation:
We are given that six integers 1,2,3,4,5 and 6.
We are given that sample space
C={1,2,3,4,5,6}
Probability of each element=
We have to find that 
Total number of elements=6
={1,2,3,4}
Number of elements in
=4

Using the formula

={3,4,5,6}
Number of elements in
=4

={3,4}
Number of elements in 

{1,2,3,4,5,6}

Answer:
x = 175 km
Step-by-step explanation:
We can use ratios to solve this problem. Put the map distance over the real life distance.
1 cm 7 cm
-------- = ---------
25 km x km
Using cross products.
1 * x = 7 * 25
x = 175 km
We know how much 16 keychains is, now we need to find how much one is.
19.68 / 16 = $1.23
$1.23 is the price of one keychain, now you can multiply that by 25 to see how much 25 keychains cost.