Question 1052269
Let {{{ x }}} = number of years after 1900
Calll 1900 {{{ x = 0 }}}
Then 1990 is {{{ x = 90 }}}
Let {{{ y }}} = height in feet
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You are gven the points
( 0, 33 )
( 90, 33.08 )
Use general point-slope formula
{{{ ( y - 33 ) / ( x - 0 ) = ( 33.08 - 33 ) / ( 90 - 0 ) }}}
Multiply both sides by {{{ 90x }}}
{{{ 90*( y - 33 ) = .08x }}}
{{{ 90y - 2970 = .08x }}}
{{{ 90y = .08x + 2970 }}}
{{{ y = .000889x + 33 }}} ( equation to use )
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Check:
does it go through ( 90, 33.08 ) ?
{{{ 33.08 = .000889*90 + 33 }}}
{{{ 33.08 = .08001 + 33 }}}
{{{ 33.08 = 33.08001 }}}
close enough
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(a)
{{{ x = 61
{{{ y = .000889x + 33 }}}
{{{ y = .000889*61 + 33 }}}
{{{ y = .0542 + 33 }}}
{{{ y = 33.0542 }}} 
In 1961, the height will be 33.05 ft
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(b)
{{{ y = 35 }}}
{{{ 35 = .000889*x + 33 }}}
{{{ .000889x = 2 }}}
{{{ x = 2250 }}}
{{{ 1900 + 2250 = 4150 }}}
The height will be 35 ft in 4150
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check my math