Question

a bag contains 5 pencils and some pens. if the probability of getting a pen is double that of pencil ,find the number of pens in the bag

Answer 1

Answer:

Let there be x no. of pens in the bag.

Therefore,

Total number of pens in the bag = (5 + x)

Now,

P1 =Probability of drawing a pens == \frac{x}{5 + x}=

5+x

x

P2 =Probability of drawing a pencil == \frac{5}{5 + x}=

5+x

5

According to the question,

P1 = 2 × P2

≈>\frac{x}{5 + x} = 2 \: \times \frac{5}{5+ x}

5+x

x

=2×

5+x

5

\frac{x}{5 + x} = \frac{10}{5 + x}

5+x

x

=

5+x

10

Cross multiple each other we get,

x(5 + x) = 10(5 + x)x(5+x)=10(5+x)

\huge \boxed{x = 10}

x=10

Hence, there are 10 pens in the bag.

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Answer 2

Step-by-step explanation:

Let there be x no. of pens in the bag.

Therefore,

Total number of pens in the bag = (5 + x)

Now,

P1 =Probability of drawing a pens == \frac{x}{5 + x}=

5+x

x

P2 =Probability of drawing a pencil == \frac{5}{5 + x}=

5+x

5

According to the question,

P1 = 2 × P2

≈>\frac{x}{5 + x} = 2 \: \times \frac{5}{5+ x}

5+x

x

=2×

5+x

5

\frac{x}{5 + x} = \frac{10}{5 + x}

5+x

x

=

5+x

10

Cross multiple each other we get,

x(5 + x) = 10(5 + x)x(5+x)=10(5+x)

\huge \boxed{x = 10}

x=10

Hence, there are 10 pens in the bag.