Question

1. In a certain area, 50% of the households are using electricity as a source of energy, 30% are using paraffin and 20% are using coal. The users of electricity use 25% for cooking, 25% for lighting, 20% for heating and 30% for small appliances. Coal is used only for cooking, and paraffin is used for cooking (50%),heating (25%) and lighting (25%).

A, summarise all the possible energy usage outcomes using a tree diagram and write the probability values on the branches.
B, what is the probability that a randomly chosen household will be using electricity for lighting?

Answer 1

A. Tree diagram

B. $P(E\cap L)$

L-Lighting

E- Electricity

$P(E\cap L)=P(E)\times P(L)$

$=0.5\times 0.25$

$=0.125$