Given the sequence: 4.5, 5.75, 7, 8.25, Find the common difference

Successful implementation of a new system is based on three independent modules. module 1 works properly with probability 0.96. for modules 2 and 3, these probabilities equal 0.95 and 0.90. compute the probability that at least one of these three modules fails to work properly.

17 in long 1.3 ft wide and 8in high what is the volume

What is the missing step in this proof ?