Which costs less per kilogram: 3.25 kg of buttons for 2.11 or 4.45 kg of metal snaps for $3.65?

Question

which costs less

Answer 1

To answer the question, you need to find the unit price - or price per kilogram - of the buttons and the snaps.  To find the unit price, divide the total price by the number of kilograms:

 

Unit Price Buttons = ($2.11)/(3.25 kg) = ______?

 

Unit Price Snaps = ($3.65)/(4.45 kg) = _______?

Answer 2

You need to divide the $ amount by the # of kilograms to find the cost per kg.

 

$2.11 / 3.25 kg = 0.6492...

 

The result is a money amount, so round the result to the hundredth place...

 

Cost per kg (buttons) = $0.65

 

Do the same for the metal snaps:

 

$3.65 / 4.45 kg = $0.82

 

Now both are in the same form, cost-per-kilo, and we can compare them:

 

0.82 > 0.65

 

Therefor metal snaps cost more per kg than buttons.

Answer 3

So the mathematical equations are:

2.11/3.25

and

3.65/4.45

 

To do the division by hand, move the decimal point to the right on both the divisor and dividend two places so the equations are now:

 

211/325= $0.65 / kg (rounding to the nearest hundredth)

and

365/445= $0.82 / kg

 

Therefore, since $0.65 is less than $0.82.  The buttons cost less than the metal snaps per kilogram.