Answer:
0.45
Step-by-step explanation:
For a uniform distribution,

where a is the minimum and b the maximum\\
cumulatively,
Step-by-step explanation:
Solve the bracket first. starting with multiplication and then subtraction
0.00035 + (4.2 x 10-5)
0.00035 + (42-5)
0.00035 + 37
0.01295
$0. She got the $40 ring and then gave it back. 40-40=0.