Are you comfortable with ratios? Try this!

[EbrahimHashem]

A certain jar contained only pennies and nickels. After 3 pennies were removed, how many nickels remained in the jar?

(1) The original ratio of pennies to nickels in the jar was 7:4.
(2) After the 3 pennies were removed, the ratio of pennies to nickels in the jar was 3:2.


HAVE FUN

[ssmiles08]

I have to say C on this one.

Choice 1 gives the ratio before, but not after: Insuff

Choice 2 gives the ratio after, but not before: Insuff

together:

(7x-3)/4x = 3/2

14x - 6 = 12x

x = 3

nickels remaining is 2x = 6 remaining nickels

[mikeCoolBoy]

IMO C

statement 1 says that the original ratio was 7:4

then the jar could have contained 7 pennies and 4 nickels or 14 pennies and 8 nickels or any other combinations.
insufficient.

statement 2 says that the new ratio is 3:2
this means that the new jar can contains 3 pennies and 2 nickels or 6 pennies and 4 nickels or any other combinations.

The combinations for the original jar could have been
6 pennies and 2 nickels
9 pennies and 4 nickels
....
insufficient

both statements together.

We now that the number of nickels is the same and that the total number is 3 less than the previous one.

N = number of nickels

Initially the jar contained 7/4N + N
after removing 3 pennies the jar contains 3/2N + N

therefore 7/4N + N -3 = 3/2N + N ---> N= 12

[ssmiles08]

I have to say C on this one.



nickels remaining is 2x = 6 remaining nickels

Sorry my mistake:

x = 3

12 nickels remain: 4x = 4(3) = 12

[aj5105]

Statement (1)

P/N = 7x/4x

Insufficient


Statement (2)

(P - 3)/N = 3x/2x

Insufficient


(1) + (2)

Substitute for P,we get N = 12

Sufficient

(C)

[brick2009]

1.) P/N = 7/4 (insufficient)

2.) (p-3)/N = 3/2 (again insufficient on its own)

simplifying: p/N -3/N = 3/2
7/4 -3/N = 3/2

N = 12, P = 21

C