In a process for manufacturing glassware, glass stems are sealed by heating them in a flame. The temperature of the flame varies a bit.

In a process for manufacturing glassware, glass stems are sealed by heating them in a flame. The temperature of the flame varies a bit. Here is the distribution of the temperature X measured in degrees Celsius: Temperature X 540o 545o 550o 555o 560o Probability 0.1 0.25 0.3 0.25 0.1 d. What is the standard deviation of the number of degrees off target, X-550? 4