SOLUTION: I am not even sure I am asking this in the right section, but you guys have been great can you help me with this problem and show how you did it. We are covering "interpolation"

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Question 29616: I am not even sure I am asking this in the right section, but you guys have been great can you help me with this problem and show how you did it. We are covering "interpolation" Thanks so much I dont know what I would do without this site.
here is the table I have been given
age Monthly life insurance premium per $20,000 coverage
20 4.00
30 6.32
40 8.64
50 10.96
60 13.28
how old is the person if their premium for $20,000 in coverage is $6.90
Answer by checkley71(8403) (Show Source):
You can put this solution on YOUR website!
ASSUMING THE RATE IS LINEAR BETWEEN 30 & 40 YEARS THEN
8.64-6.32=2.32 & 6.90-6.32=.58 WE HAVE A RELATIONSHIP OF .58:2.32 OR 1:4
THEREFORE THE AGE FOR THRE 6.90 RATE IS 1/4 OF THE 10 YEAR SPAN OR 2.5 YEARS
BEYOND 30 THEREFORE THE AGE FOR THE 6.90 RATE IS 32.5 YEARS.