Answer:
0.14% probability of a person guessing the right combination
Step-by-step explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
The order in which the numbers are selected is important. For example, 1,3,2 is a different combination than 3,1,2. So we use the permutations formula to solve this question.
Permutations formula:
The number of possible permutations of x elements from a set of n elements is given by the following formula:

Desired outcomes:
One right combination, so 
Total outcomes:
10 numbers from a set of 3. So

What is the probability of a person guessing the right combination?

0.14% probability of a person guessing the right combination
1x300
2x150
3x100
In terms of length width for the above .
Answer:
8. X = 10.5 and 19. X = 5
Step-by-step explanation:
8. You know that a triangle interior angles should add up to 180° so:
(10x - 11) + (3x - 2) + (3x + 1) = 180
180 = 16x - 12
168 = 16x
The you divide each side by 16:
168 ÷ 16 = 16x ÷ 16
X = 10.5
10. You know that a straight line equals 180° and interior angles add up to 180° so:
1st you do 180 - 151 = 29°
2nd (11x - 1) + (20x - 3) + (29) = 180
180 = 31x + 25
155 = 31x
The you divide each side by 31:
155 ÷ 31 = 31x ÷ 31
X = 5
The answer to this problem is simple to find the answer we must see the keywords in the sentence on of is how many which can mean addition/multiplication so here the problem is increasing in a rate of 3 3x1=3
3x2=6 3x3=9 and so on 3x7=21 your answer is 21