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

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.

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

Postby jonesbetty on Mon Nov 07, 2011 10:08 pm

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.
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Re: in 1920, the record for a certain race was 46.8 sec.  TOPIC_SOLVED

Postby little_dragon on Mon Nov 07, 2011 11:45 pm

jonesbetty wrote: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
:wave:
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