Fifteen coupons are numbered $1$ to $15$. Seven coupons are selected at random one at a time with replacement. The probability that the largest number appearing on a selected coupon is $9$ is:
A$\big(\frac{3}{7}\big)^7$
B$\big(\frac{1}{15}\big)^7$
C$\big(\frac{8}{15}\big)^7$
D
None of these
Download our app for free and get started
D
None of these
The sample space $= 15^7$ for selecting seven coupons from $15$ coupons.
Maximum number on selected coupon is $9$ can be made by $9^7$ ways.
A number selected on second card is less than $9$ can be made by $8^7$ ways.
Required probability $=\frac{9^7-8^7}{15^7}$
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Choose the correct answer from the given four options. A box contains 3 orange balls, 3 green balls and 2 blue balls. Three balls are drawn at random from the box without replacement. The probability of drawing 2 green balls and one blue ball is:
A letter is known to have come either from $\text{LONDON}$ or $\text{CLIFTON};$ on the postmark only the two consecutive letters $ON$ are ellegible. The probability that it came from $\text{LONDON}$ is:
The probabilities of a student getting I, II and III division in an examination are $\frac{1}{10},\frac{3}{5}$ and $\frac{1}{4}$ respectively. The probability that the student fails in the examination is.
A box contains 6 nails and 10 nuts. Half of the nails and half of the nuts are rusted. If one iten is chosen ar random, the probability that it is rusted or is nail is