Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.2. If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 9 pins is at least 51?

i'm not sure i quite understand, could you provide more information?

imma say 16%. sorry if its wrong. i'm doing the same stuff right now

step-by-step explanation:

step-by-step explanation:

consider the parallelogram shown in the attached image.

in the parallelogram hijk, the length of hk is given as,

from the properties of parallelogram we know that the opposite sides of a parallelogram are parallel to each other and are equal in measure.

therefore, the length of the side ij must be equal to the length of the side hk and that is .

hence, the expression for the length of ij confirms that hijk is a parallelogram.