Question

Keith wants to join liberty record club, which is offering new members a $20 membership fee and a cost of only $6.20 per CD. On the other hand, patriot music club charges no membership fee and cost of each cd is $8.10. Deanna wants to join patriot. Keith and Deanna are married, so they don't need to both join clubs. How many CD's would they need to buy before liberty would be cheaper? Use a guess and check method.

Answer 1

Keith want to join record library club which is offering membership at fee of 20$

Than cost per cd would be 6.2$

But other hand patriot club not charge any membership fee but

cost per cd would be =8.1$

Denna want to join patriot. Keith and denna are married.

So they don't need to join both.

How many cd to buy before library would be cheaper

So patriot is charging 1.9$ per cd more than liberty (8.1-6.2)

Further
liberty charge membership fee of $20

How many cd to buy =20/1.9

=10.52 cd

Up to 10 cd patriot is cost effective but when we purchase 11th cd it by amount of primium i.e.1.9 recover more than what membership fee charging library club 1.9*11=20.9$

So answer is 10.52 cd or 10 cd because friction of cd is not available.