Murphy loves pistachio nuts. Every Saturday morning, she walks to the market and buys a bunch. Last week, she bought two pounds and paid $7.96, and this week she bought only one-half pound and paid $1.99.

a. Is the relationship between the pounds of pistachio nuts and the cost a proportional relationship? How do you know? Explain.

b. What the unit rate for pistachio nuts? How do you know?

c. Next week, Murphy plans to buy five pounds so that she can share the nuts with her visiting cousins. How much will the five pounds cost her? Show your work and/or explain.