A Week of Readings, Two Scales

A weather station logs the midday temperature on six days, in degrees Celsius:

$12,\; 25,\; 18,\; 7,\; 21,\; 15$

Before publishing, every reading is converted to degrees Fahrenheit using

$F = 1.8\,C + 32$

What is the range of the six converted (Fahrenheit) readings?

Answer in degrees Fahrenheit, rounded to one decimal place.