Thursday

November 27, 2014

November 27, 2014

Posted by **Rebekah** on Tuesday, December 13, 2011 at 3:06am.

Help me please!

- Math for Liberal Arts -
**bobpursley**, Tuesday, December 13, 2011 at 8:08amWhat is 3*8-3*5?

- Math for Liberal Arts -
**Steve**, Tuesday, December 13, 2011 at 12:19pmNot quite sure how to subtract times using an hourglass. Can't drain the 8' one and then subtract the 5' one.

However, if we do the following, I think it works. There may be more elegant ways:

The three columns show the running time, and the operations of turning glasses, with their remaining sand

time 8' 5'

0 8 5

5 3 0

turn 5'

8 0 2

turn 8'

10 6 0

turn 5'

15 1 0

Now you can start cooking, with 1' of sand in the 8' glass.

After 1 minute, turn the 8' glass and let it drain.

**Answer this Question**

**Related Questions**

math, psychology, puzzle - you have a 5 minute hourglass and a 9 minute hour ...

9th grade - A glass jar holds a single germ. After one minute, the germ splits ...

physics - When it is 10:00, the hour hand on an analog clock is 300 degrees ...

math!!! - can you please check my work 19mm=? m ?=.19??? .017km=? cm ?=1700? ...

math..word problem - A number of bacteria are placed in a glass. One second ...

Math - 1.5gal/min=?qt/h Help!!!! First thing you need to do is figure out how ...

Liberal Arts? - I'm in middle school, my sister, (Senior in hs) keeps telling me...

geometry - show that minute hand gains five degree thirty minutes on hour hand ...

maths - show tha minute hand of a clock gains 5 degree 30 minutes over the hour ...

trigonometry - a clock has a dial face of 12 inches radius the minute hand is 9 ...