A File Has Data on 600 College Students

Short Answer

A file has data on 600 college students. One of the variables in the data file is the brand of the first car the student owned. 300 students had never owned a car and, thus, had missing data on this variable. Of the 300 students who had owned a car, 30 said Ford was the brand of their first car. As these terms are used in an SPSS frequency table,
A) What "percent" first owned a Ford? __________
B) What "valid percent" first owned a Ford? __________