Sebuah kantong berisi 7 kelereng bernomor 1,2,3,4,5,6, dan 7. Peluang terambil dua kelereng bernomor prima... a. 5/21 b. 6/21 c. 8/21 d. 10/21

no.prima = 2,3,5,7
n(a) = 4 di ambil 2
4c2 = 4!/(2!.2!) = 4.3.2!/(2!.2!)
= 6

n(s) = 7 di ambil 2
7c2 = 7!/(2!.5!) = 7.6 5!/(2!.5!)
= 21

p(a) = n(a)/n(s)
= 6/21

jawabannya B

semoga mmbantu