title: Create a random array with a particular average
body: <p>I am using scipy and want to create an an array of legnth n with a particular average.</p>
  
  <p>Suppose  I want an random arrays of length 3 with an average of 2.5 hence the possible options could be:
  [1.5, 3.5, 2.5]
  [.25, 7.2, .05]
  and so on and so forth...</p>
  
  <p>I need to create many such arrays with varying lengths and different averages(specified) for each, so a generalized solution will be welcome.</p>