Probability of obtaining a 5 = \(\frac{\text{frequency of 5}}{\text{total frequency}}\)


\(12+18+y+30+2y+45 = 150 \implies 105+3y = 150\) \(3y = 45; y = 15\)


Probability of 5 = \(\frac{2\times 15}{150} = \frac{1}{5}\)