Use the hodge conjucture. If the cummulative range between two positive integers a and b is +∞, show that the uniform difference is as above. Help, I'm stuck at some point.​

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?