Question

1. What is the fourth term in the expansion of (x + 4y)^6?

a) 7680x^3y^3
b) 3840x^2y^4
c)1440x^2y^4
d)1280x^3y^3

2. A bag contains 6 red marbles, 4 blue marbles, 7 green marbles, and 3 yellow marbles. A marble is drawn from the bag and is not replaced. Then a second marble is drawn. What is the probability that both marbles drawn were green?

Option A: 49/380
Option B: 49/400
Option C: 21/190
Option D: 21/200

Answer 1

For the fourth term r = 3
Fourth term = 6C3(x)^(6 - 3) (4y)^3 = 20x^3 (64y^3) = 1,280x^3y^3