The standard deviation of the set is 5.2
To find standard deviation, we take the square root of the variance.
Answer: 
This is the same as writing (n-m)/n
Don't forget about the parenthesis if you go with the second option.
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Explanation:
The probability that she wins is m/n, where m,n are placeholders for positive whole numbers.
For instance, m = 2 and n = 5 leads to m/n = 2/5. This would mean that out of n = 5 chances, she wins m = 2 times.
The probability of her not winning is 1 - (m/n). We subtract the probability of winning from 1 to get the probability of losing.
We could leave the answer like this, but your teacher says that the answer must be "in the form of a combined single fraction".
Doing a bit of algebra would have these steps

and now the expression is one single fraction.
Answer:
No
Step-by-step explanation:
Answer: 7.45 was used as the value due to no option
Step-by-step explanation
Since options are not available, The best value he could have rounded up to nearest tenth to give 7.5 and nearest whole number to give 7 is 7.46.
This value is 7.5 to the nearest tenth due to the last value which is greater than 5 will round the value of 4 to 5 to make 7.5.
Since the value of 4 in 7.45 is not up to 5, the value will be 7 to nearest whole number.
Answer:
x = 4
Step-by-step explanation:
You begin by making what is inside the brackets = 0. In other words you will somehow get 0 * brackets + 3 = 3
x - 4 = 0
x - 4 + 4 = 0 + 4
x = 4. When you make x = 4, the inside of the brackets = 0
1/2 * 0 = 0
So you are left with
3 = 0 + 3
and x has been made = 4
Do what's in the brackets before anything else.