ElectricPavlov

6 twos would be   12    subtract that from the total and you are left with 1.70    which is 17 ten pence(?) pieces ?

First add '3' to both sides of the equation to get

x^2 / 7 = 23     then multiply both sides by 7 to get:

x^2 = 161        Now, take the sqrt of both sides

x = sqrt(161) = 12.69

But according to all of our former banking questions the interest rate would be 100% compounded daily for 30 days with an P of 1 cent, which would yield:

Fv = Pv (1+1)^30 = 1 (2)^30 = 107341824 at the end of the 30th day....as y'all calculated.....you are right!

I guess I would see it better as doubling it 30 TIMES as opposed to doubling it 30 DAYS.  !!!

It all depends on how you interpret the question.....I guess both could be viewed as correct.

My view:

If you put the penny in a bank (that would be day 1).....it would not be doubled until the next day (day2).  The penny does not double on the first day....it would be double after 24 hours, otherwise you are STARTING with two pennies.

But I can see it your way too...except if you have a day ZERO and then compute for 30 more days you are using 31 days, not 30.     YMMV !!!

If it starts at 1 and doubles everyday:

.01 on day 1

.02 on day 2

.04 on day 3

.08 on day 4

16

32

64

`

`

`

536,870,912 pennies on day 30

Dimensional analysis again....you are given   $     and   Hours     and you want   $/hr     so....divide what you are given:

$/hr   =  $ 42.25  /  6.5 hr   =  6.76  $/hr

A  LOT of the posted questions on this forum can be simply answered if you do dimensional analysis and understand how to multiply and divide fractions.....this one is an example....your final answer is to be 'seconds'

you are given    'meters'     and 'meters/second'             Do they not teach 'dimensional analysis' any longer?????

If you divide 'meters'   by 'meters/second'    the 'meters' will cancel and you are left with 'seconds' and you have your answer.....this is REALLY good for checking your answers in ALGEBRA PHYSICS ENGINEERING etc....ALWAYS include your units in the answer !!!!!!!!!!!!!!!!!!!

m  /   m/s   =   m  x   s/m     the  m cancels and you are left with  's'

1.5 x10^11 m  /   3x10^8 m/s  =     ????  s         =     0.5 x 10^3  seconds  =  500 seconds    ( 8.33 minutes)

What is the exponent?    Doubles everyday?   Triples? etc

Add 'x' to both sides and you will have   x = 15.325/8      then  just use the calculator!