Large samples (n > 30): The tests of significance used for problems of large samples are different from those used in case of small samples as the assumptions used in both cases are different. The following assumptions are made for problems dealing with large samples: (i) Almost all the sampling distributions follow normal asymptotically. (ii) The sample values are approximately close to the population values. The following tests are discussed in large sample tests. (i) Test of significance for proportion (ii) Test of significance for difference between two proportions (iii) Test of significance for mean (iv) Test of significance for difference between two means. Test of Significance for Proportion: In a sample of 400 parts manufactured by a factory, the number of defective parts was found to be 30. The company, however, claimed that only 5% of their product is defective. Is the claim tenable?