For a large Internet service provider (ISP), web virus attacks occur at a mean rate of 150 per day. (a) What is the approximate normal probability of at least 175 attacks in a given day? (Round your z-value to 2 decimal places and your final answer to 4 decimal places.) (b) What is the approximate normal probability of fewer than 125 attacks? (Round your z-value to 2 decimal places and your final answer to 4 decimal places.) (c) Is the normal approximation justified? multiple choice 1 Yes Correct No (d-1) Use Excel to calculate the actual Poisson probabilities. (Round your answers to 4 decimal places.) (d-2) How close were your approximations? multiple choice 2 Exactly the same Quite different Fairly close Correct