Posted by **need help please** on Sunday, December 20, 2009 at 5:18pm.

ok i don't get this one

in 1920 the record for a certain race was 45.9 sec in 1980 it was 44.1 sec let r (T) = the record in the race and t= the number of years since 1920

(a) find a linear fuction that fits the data

(b) use the funcation in (a) to perdict the record for 2003 and 2006

(c) find t he year when the record will be 43.20 sec..

help please thatnks in advance

- algebra -
**Damon**, Sunday, December 20, 2009 at 5:39pm
r = m (t) + b

when year = 1920, t = 0

where t = year - 1920

45.9 = m (0) + b

so b = 45.9

44.1 = m (1980-1920) + 45.9

44.1 = 60 m + 45.9

60 m = -1.8

m = -.03

so

r =-.03 t + 45.9

when year = 2003

t = 2003 - 1920 = 83

r = -.03 (83) + 45.9

r = 43.41

that should get you started

- algebra -
**need help please**, Sunday, December 20, 2009 at 5:44pm
so what yr will it be 43.20

- algebra -
**need help please**, Sunday, December 20, 2009 at 5:47pm
so r(t)=?

- algebra -
**Damon**, Sunday, December 20, 2009 at 5:51pm
as I said

r =-.03 t + 45.9

then

43.2 = -.03 t + 45.9

.03 t = 2.7

t = 90

1920 + 90 = 2010

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