Answer
$P(guess~a~question~correctly)=\frac{9}{40}=0.225$
Work Step by Step
We are going to use relative frequency (see page 258)
Among the 40 given digits, there are nines 0 or 1 (these digits represent a correct asnwer)
$P(guess~a~question~correctly)=\frac{N(0~or~1)}{N(digits)}=\frac{9}{40}=0.225$
