Which of the following is an irrational number?

1. 2.7

2. $2.7\overline{2}$

3. $\sqrt{11}$

4. $\dfrac{2}{7}$

Which of the following is a prime number?

1. 51

2. 57

3. 71

4. 81

0.3 when expressed as a ratio of two integers, becomes :

1. $\dfrac{103}{330}$

2. $\dfrac{52}{165}$

3. $\dfrac{103}{111}$

4. $\dfrac{104}{333}$

Only by inspecting the prime factors of the denominator, state which of the following fractions will be a terminating decimal?

1. $\dfrac{7}{12}$

2. $\dfrac{2}{15}$

3. $\dfrac{3}{16}$

4. $\dfrac{4}{21}$