The tree diagram below shows all of the possible outcomes for flipping three coins.

Step-by-step explanation:

C=0.14×7,200=1008

Nadia made a total of $1008 last week in commission sales

b). To express the total amount she made in 2011, we derive the formula below;

Total amount (2011)=Average weekly commission× number of weeks in 2011

where;

Average weekly commission=$1008

number of weeks in 2011=52

replacing;

Total amount (2011)=(1008×52)=52,416

The total amount Nadia in commission in 2011=$52,416