Question

A bag contains 40 pen drives out of which x are non detective. If one pen drive is drawn at random, the
probability of drawing a non defective pen drive is y. If we replace the drawn pen drive and add 20 more
non-defective pen drives in this bag, the probability of drawing a non-defective pen drive is 4y. Find x.​

Answer 1

Answer:

x=4

Step-by-step explanation:

y=x/40----------------(1)

After replacing the drawn pen drive and adding  20 more

non-defective pen drives in this bag, the probability of drawing a non-defective pen drive

4y=(x+20)/60

4*x/40=(x+20)/60

x/10=(x+20)/60

6x=x+20

5x=20

x=4

Answer 2

Answer:

The value of x is 4.

Step-by-step explanation:

Initially, a bag contains 40 pen drives in which x are non-defective.

Probability of drawing a non-defective pen drive = y

P(Non-defective pen drive) = y

⇒ x/40 = y ______ (1)

After replacement,

20 more non-defective pen drive are added.

Then,

The total number of pen drives = 40 + 20

                                                     = 60

The total number of non-defective pen drive = x + 20

New probability of drawing a non-defective pen drive = 4y

P(Non-defective pen drive) = 4y

⇒ (x + 20)/60 = 4y

Substitute the value of y as follows:

$\frac{x+20}{60}=4\times\frac{x}{40}$

Cross multiply the equation as follows:

40(x + 20) = 60(4x)

40x + 800 = 240x

40x - 240x = -800

-200x = -800

x = 4

Therefore, the value of x is 4.

#SPJ3