How does a digits position affect its value

How to write 3 tenths and 5 tenths as a decimal

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?

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle