Question

There are 7 yellow balls, 4 green balls, 3 red balls and 6 blue balls. If a ball is selected at random what is the probability that it i not a blue ball? (a)620(b)720(c)1420(d)420

Answer 1

$|\Omega|=7+4+3+6=20\\|A|=14\\\\P(A)=\dfrac{14}{20}=\dfrac{7}{10}$