## in 1920, the record for a certain race was 46.8 sec.

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
jonesbetty
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Joined: Mon Nov 07, 2011 10:00 pm
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### in 1920, the record for a certain race was 46.8 sec.

in 1920, the record for a certain race was 46.8 sec. in 1980, it was 45.6 sec. Let R(t)=the record in the race and t=the number of years since 1920.
a) find a linear function that fits the data
b) use that function to predict the record in 2003 and in 2006
c) find the year when the record will be 44.96 sec.

little_dragon
Posts: 226
Joined: Mon Dec 08, 2008 5:18 pm
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### Re: in 1920, the record for a certain race was 46.8 sec.

in 1920, the record for a certain race was 46.8 sec. in 1980, it was 45.6 sec. Let R(t)=the record in the race and t=the number of years since 1920.
a) find a linear function that fits the data
b) use that function to predict the record in 2003 and in 2006
c) find the year when the record will be 44.96 sec.
a) they gave U 2 pts, so plug them into the slope formula: http://www.purplemath.com/modules/slope.htm
then plug this into 1 of the formulas for line eqns: http://www.purplemath.com/modules/strtlneq.htm
b)subtract 1920 from 2003 to get t
plug this in for t in formula from 'a'
get the value 4 R
do the same thing for 2006
c) plug 44.96 in 4 R
solve for t
add 2 1920 2 get yr