A new augmented reality entertainment center opened up at L.A. Live, the entertainment complex in downtown Los Angeles. It costs $10.95 to gain general admission. Once entered, a customer can play unlimited games at $4.99 per hour. The Center knows the time a customer spends at the Center is a random variable with a mean of 3 hours and a standard deviation of 1.35 hours. What is the standard deviation, to the nearest cent, of the amount of money a customer spends per visit to the Center? Round your answer to the nearest cent. Answer: 6.74

Can you please explain how to get that answer/ formulas and why and how you got it thank you!