Question

Write $A=\{x|x$ is a month of the Gregorian year having more than $30$ days$\}$ in the roster form:

• A. A = {January, March, May, July, August, December}
• B. A = {January, March, May, July, August, October, December}
• C. A = {January, February, March, April, May, June, July, August, September, October, November, December}
• D. None of these
  

Answer 1

The correct option is B A = {January, March, May, July, August, October, December}

In roster method, elements of the set are listed within the pair of brackets { } irrespective of order but element should not be repeated. Given question is about representing months which does not have 30 days. Means we have months having more or less than 30 days. So B answer is correct. Hence,

A = {January, March, May, July, August, October, December}