The normal distribution curve looks like this:
The middle line is mean and the 50% of the data are at both sides of the mean.
In our problem, the mean is "49" and we want to find the percentage of data that are less than 49.
It basically means data percentage that is less than the mean.
From the graph, we know 50% of data falls below the mean and 50% falls above the mean.
Hence,
Answer is 50%
