title: Average of the first items of tuples in a dict
body: <p>I have a dictionary in the form:</p>
  
  <pre><code>{"a": (1, 0.1), "b": (2, 0.2), ...}
  </code></pre>
  
  <p>Each tuple corresponds to (score, standard deviation).
  How can I take the average of just the first integer in each tuple?
  I've tried this:</p>
  
  <pre><code>for word in d:
      (score, std) = d[word]
      d[word]=float(score),float(std)
      if word in string:
          number = len(string)
          v = sum(score)
          return (v) / number
  </code></pre>
  
  <p>Get this error:</p>
  
  <pre><code>    v = sum(score)
  TypeError: 'int' object is not iterable
  </code></pre>