statistics questions, can you please double check me?

My answers are at the bottom.

1. A business evaluates a proposed venture as follows. It stands to make a profit of $10,000 with probability .15, to make a profit of $5,000 with probability .45, to break even with probability .25 and to lose $5,000 with probability .15. The expected profit in dollars is: A) 1500

B) 0

C) 3000

D) -1500

2. The average length of stay in a hospital is useful for planning purposes. Suppose that the following is the distribution of the length of stay in a hospital after a minor operation:

Days 2 3 4 5 6 Prob .05 .20 .40 .20 .15The average length of stay is: A) .15

B) .17

C) 3.3

D) 4.0

E) 4.2

3. Before planting a crop for the next year, a producer does a risk assessment. According to her assessment, she concludes that there are three possible net outcomes: a $7,000 gain, a $4,000 gain, or a $10,000 loss with probabilities 0.55, 0.20 and 0.25 respectively.The variance of this random variable is

A) 700

B) 7108

C) 490000

D) 50527500

4. Before planting a crop for the next year, a producer does a risk assessment. According to her assessment, she concludes that there are three possible net outcomes: a $7,000 gain, a $4,000 gain, or a $10,000 loss with probabilities 0.55, 0.20 and 0.25 respectively.

What is the standard deviation of this random variable?

A) 700

B) 7108

C) 55150000

D) 490000

1. A

2. D

3. A

4. B