Homework Help: algebra

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

ok i dont 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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