The mean time it takes for workers at a factory to insert a delicate bolt into an engine is 15 minutes. The standard deviation of time to insert the bolt is 4.0 minutes and the distribution of time is approximately normally distributed.
For a randomly selected worker, what's the approximate probability the bolt will be inserted in 19 minutes or less? Round to the nearest whole percent.
◦ 16%
◦ 18%
◦ 84%
◦ 50%