audrey meausers all 7 penciles in her pecile case and wirtes down the first 6 lengths.
11.8cm, 12.4cm , 12.5cm, 13.2cm , 13.6cm, 13.1 cm
audrey calcuates the mean length of all 7 penciles to be 13cm .
find the length of the missing pencile?
click on picture to help you
