In a study of performance ratings of ex-smokers, a random sample of 34 ex-smokers had a mean rating of 2.21and a sample standard deviation of 2.21.for an independent random sample of 86 long-term ex-smokers, the mean rating was as 1.47 and the sample standard deviation was 1.69. find the lowest level of significance at which the null hypothesis of equality of the two population means can be rejected against the two-sided alternative