Question

Imagine that you have ten small light bulbs, of which three are burned out a) in how many ways can you randomly select 4 of the light bulb b) in how many ways can you select two good light bulbs and two burned out light bulbs?

Hel needed Urgently

Answer 1

a) In order to find the ways you can randomly select 4 of them, we use Combinations:

C(10,4)
= 10!/6!4! = 210

b) Two select in a specific way, we use different combinations for the burnt out and good bulbs, and multiply them:

C(7,2) x C(3,2)
= 7!/5!2! x 3!/2!
= 7 x 3 x 3
= 63