There are 15 people to choose from and 4 places to put them in. how many of the groups include bob? (this is probability. i made up the problem because i don’t know how to do this and i have a test 4th hour! )

Aaron invested a total of $4,100, some in an account earning 8% simple interest, and the rest in an account earning 5% simple interest. how much did he invest in each account if after one year he earned $211 in interest? select one: a. $200 at 8%, $3,900 at 5% b. $3,200 at 8%, $900 at 5% c. $900 at 8%, $3,200 at 5% d. $3,900 at 8%, $200 at 5%