please show working out thanks!

11 The distribution of the amount of money spent by first-time gamblers at a major casino in Las Vegas is approximately normal in shape with a mean of $600 and a standard deviation of $120. According to the Standard Deviation Rule: a) 99.7% of first-time gamblers at this casino spend between $ and $ 97.5% of first-time gamblers at this casino spend less than $ c) 16% of first-time gamblers at this casino spend more than $ d) What percent of first-time gamblers spend less than $240