Answer:
σX = 3161
Step-by-step explanation:
The standard deviation is the square root of the multiplication of each probability multiplied by the squared difference between the values and the mean.
In this question:

Rounding to the nearest dollar, σX = 3161
If they were to win $30 they would expect to get $27 in profit.
If they were to win $10 they would expect $7.
If they were to win $0 they would expect $-3 in profit, so technically if they win nothing they lose money.
Hope I could help! :D
I think its 1/12 cause it is inches to feet.
Answer:
471.24
Step-by-step explanation: