Question

An electronic machine choose random numbers from $1$ to $30$. What is the probability that the number chosen is a triangular number?

• A. $\frac{11}{30}$
• B. $\frac{1}{10}$
• C. $\frac{1}{6}$
• D. $\frac{7}{30}$

Answer 1

The correct option is D $\frac{7}{30}$

Triangular numbers betweeen 1 and 30 are $1,3,6,10,15,21,27$ i.e., $7$ in number.
$\therefore$ Required probability=$\frac{7}{30}$