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Which of the following is the correct syntax to calculate variance of array arr using NumPy?

easy📝 Syntax Q12 of 15
NumPy - Aggregation Functions
Which of the following is the correct syntax to calculate variance of array arr using NumPy?
Anp.std(arr)
Bnp.variance(arr)
Carr.var()
Dnp.var(arr)
Step-by-Step Solution
Solution:

  1. Step 1: Recall the NumPy function for variance

    The correct NumPy function to calculate variance is np.var().

  2. Step 2: Check each option

    np.var(arr) uses np.var(arr) which is correct. np.variance(arr) uses a non-existent function np.variance(). arr.var() uses arr.var() which works only if arr is a NumPy array, but the question asks for NumPy function syntax. np.std(arr) calculates standard deviation, not variance.

  3. Final Answer:

    np.var(arr) -> Option D

  4. Quick Check:

    Variance function = np.var() [OK]
Quick Trick: Variance uses np.var(), not np.variance() [OK]
Common Mistakes:
  • Using np.variance() which does not exist
  • Confusing variance with standard deviation function
  • Using method on list instead of NumPy array

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