What is the probability that two events, a and b, will occur at the same time? answer choices: p(a or b) p(a and b) p(a)+p(b)

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

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?

Acar travels at an average speed of 52 miles per hour. how long does it take to travel 299 miles