# Thread: Standard Deviation and Temperature

1. ## Standard Deviation and Temperature

Need help with this problem!!!

You are planning to take to a trip to Montreal, Canada during the month of April and you want to bring clothing that is appropriate for the weather. The daily high temperature X in degrees Celsius in Montreal during April has expected value E(X) = 9.7oC with a standard deviation SD(X) = 3.7oC. You want to convert these Celsius temperatures to oF (degrees Fahrenheit). The conversion of X into degrees Fahrenheit Y is Y = (9/5)X + 32.

The expected value in Fahrenheit is 49.46 but how would you calculate the standard deviation into Fahrenheit??? It is not 38.66.

Thank you

2. Originally Posted by dbt294
Need help with this problem!!!

You are planning to take to a trip to Montreal, Canada during the month of April and you want to bring clothing that is appropriate for the weather. The daily high temperature X in degrees Celsius in Montreal during April has expected value E(X) = 9.7oC with a standard deviation SD(X) = 3.7oC. You want to convert these Celsius temperatures to oF (degrees Fahrenheit). The conversion of X into degrees Fahrenheit Y is Y = (9/5)X + 32.

The expected value in Fahrenheit is 49.46 but how would you calculate the standard deviation into Fahrenheit??? It is not 38.66.

Thank you
If Y = aX + b then $Var(Y) = a^2 Var(X)$ and $sd(Y) = |a| sd(X)$.