The answer is e)15 Because : to find out the possibility of drawin yellow balls we should divide the number of yellow balls to total balls,
Let y be the number of yellow balls:
\(\frac { y }{ 30 }\) and we know that the possibility is equal to \(\frac { 1 }{ 6 }\)
\(\frac { y }{ 30 } =\frac { 1 }{ 6 }\) from this equation we find y = 5.
If y=5 the number of red balls is 25. If we decrease red balls 15 total number of balls will be = 15. So since number of yellow balls did not change :\(\frac { 5 }{ 15 } =\frac { 1 }{ 3 }\)
