Suppose that the amount of time it takes the IRS to send refunds to taxpayers is normally distributed with a mean of 8 weeks and a variance of 6. How long will it take before 90% of taxpayers get their refunds? [Assume that all taxpayers send their tax returns to the IRS at the same time.] a. 23.53 weeks b. 11.14 weeks c. 15.69 weeks d. None of the other answer choices is correct. e. 15.84 weeks