title: Is there a method to multiply only certain elements in a numpy array
body: <p>Suppose I have a numpy array like so:</p>
  <pre><code>a = ([[4, 9], [38, 8], [90, 10]...[8545, 17]])
  </code></pre>
  <p>Where the first element is a location ID and the second is the amount of time spent at each location in minutes. I want to convert these times into seconds which requires me to multiply every other value by 60.</p>
  <p>As this is a very long array, what would be the most time-efficient method for converting these times?</p>