WAEC - Mathematics (2003 - No. 37)
The probabilities of a boy passing English and Mathematics test are x and y respectively. Find the probability of the boy failing both tests
1-(x-y)+xy
1-(x+y)-xy
1-(x+y)+xy
1 - (x - y) + x
Explicació
Prob (passing English) = x
Prob (passing Maths) = Y
Prob (failing English) = 1 - x
Prob (failing Maths) = 1 - y
Prob (failing both test) = Prob(failing English) and Prob(failing Maths) = (1 - x)(1 - y)
=1 - y - x + xy
=1 - (y + x) + xy
Prob (passing Maths) = Y
Prob (failing English) = 1 - x
Prob (failing Maths) = 1 - y
Prob (failing both test) = Prob(failing English) and Prob(failing Maths) = (1 - x)(1 - y)
=1 - y - x + xy
=1 - (y + x) + xy