4. for $a<0.5$

## Correct answer: for $a<1$

## Question 3

Correct

Points: 1.00 out of a maximum of 1.00

Question 4

Correct

Points: 1.00 out of a maximum of 1.00

## Question 5

Correct

Points: 1.00 out of a maximum of 1.00
Worker $A$ and worker $B$ can complete the work in 7.2 days, worker $A$ and worker $C$ in 9 days, worker $B$ and worker $C$ in 12 days. How many days will they take to complete the work if they all work together?