I gots change that jingle-jangle-jingles…


One pound of change = $15.41
 
How did I get this?
Lots of spare time and spare change. Follow along below.
 
Number of each coin for all change combinations
(using fewest number of coins) from $0.01 to $0.99
 
80        Pennies
40        Nickels
80        Dimes  
150      Quarters
 
With the number of occurrences of each coin (#ofoccur), having coin weight (cw), and coin value (cv), the following is true (if you make some bold assumptions about the change people receive, how much they put in the jar, and that no one is borrowing quarters for gumballs):

Format:
coin: cw*#ofoccur = weight in g (#ofoccur*cv = total value in $)

penny: 2.5g*80 = 200g ($0.80)
nickel: 5g*40 = 200g ($2.00)
dime: 2.268g*80 = 181.44g ($8.00)
quarter: 5.6g*150 = 840g ($37.50)

1 gram= .0352739619 oz

350 coins total = 1421.44g*.0352739619 = 50.13982044 oz = 3.13373878 lbs
(total value = $48.30)

48.30 / 3.13373878 = 15.41289922065553
 
(All values below are rounded to two decimal places)

One pound of change = $15.41

One pound of pennies = $3.07
One pound of nickels = $4.54
One pound of dimes = $20.00
One pound of quarters = $ 20.25