it takes an older computer twice as long to send out a company's email as it does a newer computer. Working together, it takes the two computers 25 minutes to send out the email. How long will take the newer computer to send out the email on its own?

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

What is the probability of drawing three queens from a standard deck of cards, given that the first card drawn was a queen? assume that the cards are not replaced.

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?