The right answer is “The classroom has 5,180 seats “
We first add the tax to the non-food items. We have ($3.00+$.50)*1.05=($3.50)*1.05=$3.675 (Which can be rounded up to $3.68, since we can't have a fraction of a cent).
Now, we add the cost of the food to $3.68. As a result, we have $3.68+$2.50=$6.18 as the total bill.
Answer:




Step-by-step explanation:
The probability mass function P(X = x) is the probability that X happens x times.
When n trials happen, for each
, the probability mass function is given by:

In which p is the probability that the event happens.
is the permutation of n elements with x repetitions(when there are multiple events happening(like one passes and two not passing)). It can be calculated by the following formula:

The sum of all P(X=x) must be 1.
In this problem
We have 3 trials, so 
The probability that a wafer pass a test is 0.7, so 
Determine the probability mass function of the number of wafers from a lot that pass the test.



