please stat problem help

2 questions....

1. Suppose that the distribution of annual salaries for sales associates at this store is bell-shaped. Use the empirical rule to calculate the percentage of sales associates with salaries between $30,000 and $35,000.

answer is: approximately 68%
how is that? how do you come up with that answer? I'm lost and confused.

2. A company plans to interview 10 recent graduates for possible employment. The company has 3 positions open. How many groups of 3 can the company select?

answer is: 120
I attempted to us the counting rule for combinations, but I came up with a totally different answer....can someone please go through the step by step process of solving this one please?