Question 754391: A piggy bank contains exactly $50 in $1 and $2 coins.
Fanny counted 30 coins.
Frank counted 31 coins.
Who's right? Found 2 solutions by Alan3354, dkppathak:Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! A piggy bank contains exactly $50 in $1 and $2 coins.
Fanny counted 30 coins.
Frank counted 31 coins.
Who's right?
------------------
n = $1 coins
t = $2 coins
----
n + t = 30
n + 2t = 50
------------- Subtract
-t = -20
20 $2 coins
10 $1 coins
Total $50
================
n + t = 31
n + 2t = 50
------------- Subtract
-t = -19
19 $2 coins
12 $1 coins
Total $50
Could be either way.
You can put this solution on YOUR website! let $1 is x coins
and as per fanny case
$2 are 30-x coins
x+2(30-x)=50
x+60-2x =50
-x=-10
x=10
so $1 are 10 coins
and $2 20 coins
as per frank case
let $1 is x coins and
$2 are 31-x coins
x+2(31-x)=50
x+62-2x =50
-x=-12
x=12
$2 coins will be 19 coins
in this problem
both counting are correct for given conditions
for fanny 30 coins $1 are 10 coins and $2 are 20 coins
and as per frank counting
$1 coins will be 12 and
$2 coins will be 19
answer
