Answer: [tex]\dfrac{25}{56}[/tex]
Step-by-step explanation:
Given: P(dot sent) = [tex]\dfrac37[/tex]
and P(dash sent) = [tex]\dfrac47[/tex]
P(dot received) = P(dot received ∩ dot sent)
+ P(dot received ∩ dash sent)
= P(dot received | dot sent)P(dot sent) + P(dash received | dash sent)P(dash sent) [By conditional probability formula]
[tex]=\dfrac78\times\dfrac37+\dfrac18\times\dfrac47=\dfrac{25}{56}[/tex]
Hence, the probability that the received symbol is a dot = [tex]\dfrac{25}{56}[/tex]