Question

a bag has some green pens and 12 red pens .A pen is taken out of the bag and the probability of that the pen is red is 3/5. The number of green pen in the bag is​

Answer 1

${\boxed{\sf{Probability = {\dfrac{Favourable \ outcomes}{Total \ outcomes}}}}}$

$\sf{Probability \ (getting \ red \ pens) = {\dfrac{3}{5}} \qquad (Given)}$

$\sf{Number \ of \ red \ pens = 12}$

$\sf{\therefore \quad {\dfrac{3}{5}} = {\dfrac{12}{Total \ pens}}}$

$\sf{\underline{Transposing}}$

$\sf{Total \ pens = {\dfrac{12 * 5}{3}}}$

$\sf{Total \ pens = 20}$

$\sf{Now,}$

$\sf{Green \ pens = Total \ pens - Red \ pens}$

$\sf{\Rightarrow \ 20 - 12}$

$\sf{\Rightarrow \ 8}$

$\sf\red{The \ bag \ contains \ 8 \ green \ pens.}$