3.9(10s + 5) , solve for s

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

Write the equation in general quadratic form: plz !

In a timed typing test lara typed 63 words per minute. estimate the number of words she should be able to type in half in hour show your work