You-flip-two-fair-six-sidded-dice-and-add-the-number-of-spots-what-probability-of-getting-a-number-divisible-by-2-but-not-by-5-

Question Number 131062 by benjo_mathlover last updated on 01/Feb/21

You flip two fair six - sidded dice and add

the number of spots . what probability of getting

a number divisible by 2 but not by 5 ?

Answered by EDWIN88 last updated on 01/Feb/21

W r i t e L_{n} f o r e v e n t h e n u m b e r i s

d i v i s i b l e b y n . N o w P (L_{2}) = 1 / 2 .

(c o u n t t h e c a s e; o r m o r e e l e g a n t l y n o t i c e

t h a t e a c h d i e h a s t h e s a m e n u m b e r o f

o d d a n d e v e n f a c e s a n d w o r k f r o m t h e r e)

N o w P (L_{2} - L_{5}) = P (L_{2}) - P (L_{2} \cap L_{5})

b u t L_{2} \cap L_{5} c o n t a i n s o n l y t h r e e

o u t c o m e s (6, 4), (5, 5) a n d (4, 6) s o

P (L_{2} - L_{5}) = \frac{1}{2} - \frac{3}{36} = \frac{5}{12}

Facebook Tweet Pin