Under ideal conditions some common bacteria can divide and double their numbers in less than one half hour. suppose one spring day at 6am a few such bacteria fall into a can of strawberry surup in a broken garbage bag behind a snack bar. these conditions-warmth, moisture, and lots of food- are perfect growth, and the population doubles every 20 minutes. by 6pm the bacteria overcrowds and dry the food and is gone. at what time did the can of syurup become half full?

If the population doubles every 20 minutes, and the can is full at 6:00PM, then the can must have been half full 20 minutes before 6:00PM or 5:40PM 

Likewise the can is: 
Full at 6:00PM 
Half full at 6:00-0:20 = 5:40PM 
1/4 full at 5:40 - 0:20 = 5:20PM 
1/8 full at 5:20 - 0:20 = 5:00PM 
1/16 full at 5:00 - 0:20 = 4:40PM

Your answer is going to be d.

Iwould suggest the myers-briggs type indicator because the railroad unions are looking for which are focused introverts. the mbti was designed to provide a lot of information about what a person likes and what their personality based on the four-dimension scale. also for an employer it has been extremely to predict how an employee would act in a professional setting. this is what the railroad unions are looking for. they want the railroad workers to be focused and skillful to ensure the safety of everyone around them. but the other assessments don't match the criteria for the unions. like the measure disorder, emotions and self-esteem while the rorschach and tat tests are both projective tests that mainly measure someone’s personality. also, because this job is not easy, it is vital to make sure the employers are hiring the right people for the job.