If bacteria divide every 30 min, and you start with a single bacterium at noon, how many bacteria will you have just after 2: 00 pm?

You'd start with 1 at 12:00 

Then at 12:30 that would divide into 2 

At 1:00 those 2 would divide into 2 more and you'd have 4 

At 1:30 the four would divide into 2 as well, giving you 8 

At 2:00 The 8 would divide into 2 once again, and you'd have (end) with 16 

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.