This book is the collection of notes of quantitative techniques on following topics : Probability: Definition and explanation, Basic concepts of probability, probability scale, calculation of probability of an event, Combination in theory of probability, Multiplication theorem, conditional probability, multiplication theorem for dependent events, combined use of addition multiplication theorem, Baye's theorem, use of Baye's theorem, statement and proof of Baye's theorem: Probability distributions (Binomial , Poisson, Normal and exponential), Definition, application, and illustrative solved examples.