Tìm thành phần chưa biết trong tỉ lệ thức, dãy tỉ số bằng nhau:x+2÷x+1=4x+5÷4x

Hello people, i have a math question that i need with, me, i will give the correct one brainiest, and for the other correct people, a and 5 stars.

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?

The trigonometric ratios sine and secant are reciprocals of each other