Modifying the Coin Class

1. Create a new class named BiasedCoin that models a biased coin (heads and tails are not equally likely outcomes of a flip). To do this modify the coin class from the text (in the file Coin.java) as follows:
   • Add a private data member bias of type double. This data member will be a number between 0 and 1 (inclusive) that represents the probability the coin will be HEADS when flipped. So, if bias is 0.5, the coin is an ordinary fair coin. If bias is 0.6, the coin has probability 0.6 of coming up heads (on average, it comes up heads 60% of the time).
   • Modify the default constructor by assigning the value 0.5 to bias before the call to flip. This will make the default coin a fair one.
   • Modify flip so that it generates a random number then assigns face a value of HEADS if the number is less than the bias; otherwise it assigns a value of TAILS.
   • Add a second constructor with a single double parameter -- that parameter will be the bias. If the parameter is valid (a number between 0 and 1 inclusive) the constructor should assign the bias data member the value of the parameter; otherwise it should assign bias a value of 0.5. Call flip (as the other constructor does) to initialize the value of face.

2. Compile your class to make sure you have no syntax errors.

3. Modify the Runs program from the last exercise to use a BiasedCoin.