I am a business student and have a task on standard deviation, I have absolutely no idea how to complete it:

'You and some of your friends from your course are putting on a charity event. Last year different groups raised a mean of £600 with a standard deviation of £120. You want to be in the top 10% of groups this year. Based on last years outcome, how much do you need to raise? Assume money raised followed a normal distribution, use a diagram and show your working'

Any help would be fantastic! Really need saving here.