SC Guide 8, 3rd ed - page 63, 62 and 68

[ooisuankim]

In the SC Guide 8, 3rd ed at page 63, I understand that if I join 2 main clauses with and, I have to put a coma before the and.

1. Applying this rule, why is it that the following sentence at page 62: - "The division was opening ofices, hiring staff and investing in equipment" - that there is no comma after "hiring staff"?

2. How does that differ from the next sentence: - "They wanted to increase awareness, spark interest, and motivate purchases" - wherein there is a comma after "spark interest".

- Applying the logic of this sentence, at page 68 of the same book, why is it that there is no comma after "notify investors" for the "right" sentence under heading (2) Infinitives:- "It is critical to suspend activites, notify investors and say nothing".

Would appreciate any of the instructors in clarifying the above. Thanks.

[StaceyKoprince]

1. That's a typo. There should be a comma there. Same thing on p.68. Good eye. :)