title: TestDome Data Science: Not getting correct answer
body: <p>I tried to answer this <a href="https://www.testdome.com/questions/data-science/marketing-costs/11855?questionIds=13588,11855&amp;generatorId=65&amp;type=fromtest&amp;testDifficulty=Easy" rel="noreferrer">question</a> from TestDome and got 250877.19298245612 instead of 250000 as suggested. Please let me what went wrong. Thanks</p>
  
  <pre><code>import numpy as np
  from sklearn import linear_model
  
  class MarketingCosts:
  
      # param marketing_expenditure list. Expenditure for each previous campaign.
      # param units_sold list. The number of units sold for each previous campaign.
      # param desired_units_sold int. Target number of units to sell in the new campaign.
      # returns float. Required amount of money to be invested.
      @staticmethod
      def desired_marketing_expenditure(marketing_expenditure, units_sold, desired_units_sold):
          X = [[i] for i in units_sold]
          reg = linear_model.LinearRegression()
          reg.fit(X, marketing_expenditure)
          return float(reg.predict(desired_units_sold))
  
  #For example, with the parameters below the function should return 250000.0.
  print(MarketingCosts.desired_marketing_expenditure(
      [300000, 200000, 400000, 300000, 100000],
      [60000, 50000, 90000, 80000, 30000],
      60000))
  </code></pre>