Question

7. A shopkeeper has 100 memory cards in a box. Among then 15 memory cards Are
defective when a person came to the shop to buy a memory cards, the
shopkeeper draw a memory card at random from the box then
(i) What is the probability that memory card is defective?
(ii) After drawing the first memory card which is defective, it is not placed
back in the box”. Then what is the probability that this memory card is
not defective.​

Answer 1

Answer:

1) 100/15

85/15

15 card is defects

Answer 2

(i) P(Getting a defective memory cards) = $\dfrac{15}{100} or \dfrac{3}{20}$

(ii) P(Getting a not defective memory cards) = $\dfrac{85}{100} or\dfrac{17}{20}$

Step-by-step explanation:

Given,

Total memory cards in a box = 100

∴ Total number of possible outcomes = 100

and defective memory cards in a box = 15

(i) To find the probability that memory card is defective = ?

Number of favourable outcomes = 15

∴ P(Getting a defective memory cards) = $\dfrac{Number of favourable outcomes}{Total number of possible outcomes}$

= $\dfrac{15}{100}$ or$\dfrac{3}{20}$

(ii) To find the probability that memory card is not defective = ?

∴ P(Getting a not defective memory cards) = 1 - P(Getting a defective memory cards)

= $1 - \dfrac{15}{100} = \dfrac{100-15}{100} = \dfrac{85}{100} or \dfrac{17}{20}$