Admin Control Panel

New Post | Settings | Change Layout | Edit HTML | Moderate Comments | Sign Out O level A level A A1 A2 home private tuition physics chemistry mathematics maths biology trigonometry physics H2 H1 Science Score tutor tuition tuition tutoring tuition biology economics assessment exam exams exampapers exam papers NIE JC Secondary School Singapore Education tutor teach teacher school student agency

O lvl E Maths: Probability

RGS Practice Question

Two dice are thrown. One is biased so that the probability of throwing a 6 is 1/16 and the probabilities of throwing the other five numbers are all equal. The other die is unbiased. Calculate, as a fraction in its lowest term, the probability that
(i) both numbers thrown are not 6,
(ii) at least one of the two numbers thrown is a 6,
(iii) exactly one of the numbers thrown is a 4.

*************************

Answer:

(i) P(both numbers thrown are not 6)
= P(1st dice not 6 and 2nd dice not 6)
= 15/16 * 5/6
= 25/32

(ii) P(at least one of the two numbers thrown is a 6)
= 1 - P(both numbers thrown are not 6)
= 1 - 25/32
= 7/32

(iii) For the biased dice, the probability of getting 1, 2, 3, 4 or 5 is (1 - 1/16)/5 = 3/16

P(exactly one of the numbers thrown is a 4)
= P(1st dice is 4, and 2nd dice is not 4) + P(1st dice is not 4, and 2nd dice is 4)
= 3/16 * 5/6 + 13/16 * 1/6
= 5/32 + 13/96
= 7/24



Related Articles by Categories



Singapore's first free online short to
medium questions and solutions database



Related Posts with Thumbnails