Real Numbers MCQs

Q1. A baker at a flour mill wraps a string once around a circular rim and notes the value pi times the diameter. How should this number be classified?

• A.a prime number
• B.an integer
• C.irrational
• D.rational

Answer: C. irrational

A number is rational if it is p/q with integers p,q (q!=0), i.e. terminating or repeating; otherwise irrational. Here pi is non-terminating non-repeating, so the number is irrational.

Q2. An electrician at a survey camp finds the slant of a 1-by-2 rectangle to be sqrt(5) units. How should this number be classified?

• A.rational
• B.irrational
• C.an integer
• D.a prime number

Answer: B. irrational

A number is rational if it is p/q with integers p,q (q!=0), i.e. terminating or repeating; otherwise irrational. Here sqrt(5) is the root of a non-perfect square, so the number is irrational.

Q3. A jeweller in a foundry computes the side of a 49 square-centimetre tile as sqrt(49). How should this number be classified?

• A.rational
• B.an integer
• C.a prime number
• D.irrational

Answer: A. rational

A number is rational if it is p/q with integers p,q (q!=0), i.e. terminating or repeating; otherwise irrational. Here sqrt(49)=7, an integer, so the number is rational.