According to the IRS, the average income tax refund for 2017 tax year was $2,780.Assume the refund per person follows the normal curve distribution with a standard deviation of $950.

1. What is the probability that a randomly selected tax return from the 2017 tax year will be
2. More than $2,000?
3. Between $1,600 and $2,500?
4. Between $3,200 and $4,000?