I have an example about droop and it asks to calculate final frequency in a grid after one generator power generation is lost. The answer is given as 59.889 Hz; however, I am calculating as 59.99 Hz. What am I missing?

The question is 

    Assume a grid has lost one generator (42MW) and the remaining
    generation is 1132 MW. All generators have governors set to 5% droop.
    What is the final frequency?

This is the given formula 

$$
\Delta(f) = \frac{R.\Delta P_{gen,MW}}{\sum S_{online, MVA}}.
$$

$$
\Delta(f) = \frac{0.05 x 42}{1132}=0.0019.
$$
Final frequency is 60-0.0019=59.9981