18/20=K/110
20K= 110*18
20K= 1980
K= 99
The '68-95-99.7' rule says
-About 68% of values fall within one standard deviation of the mean.
-About 95% of the values fall within two standard deviations from the mean.
-Almost all of the values — about 99.7% — fall within three standard deviations from the mean.
Here 
Therefore, the probability

The required probability

Answer:
2 over 7
Step-by-step explanation: