Entropy when having symbols with same probability I am trying to work out this problem:

Assume that we are transmitting data from a dictionary of 15 symbols. Let the 
probability of sending one symbol be the same as that of sending any other 
symbol. Calculate how often we need to fetch a symbol to transmit information at 
a rate of 5 bits/s. 

How can this be found?
HINT: Compute the entropy $H$ of your source and note that in your case it represents the  number of bits required to represent each symbol. Then from
$\quad H$ [bits/symbol] $\times$ $x$ [symbols/second] = $5$ [bits/second]
compute $x$.