If s varies directly as r and inversely as t and s=10 when r=5 and t=3, for what value of t will s=3 when r=4?

1 Answer
Jul 14, 2017

t=8t=8

Explanation:

"the initial statement is " spropr/tthe initial statement is srt

"to convert to an equation multiply by k the constant of"to convert to an equation multiply by k the constant of
"variation"variation

rArrs=kxxr/t=(kr)/ts=k×rt=krt

"to find k use the condition given"to find k use the condition given

s=10" when "r=5" and "t=3s=10 when r=5 and t=3

s=(kr)/trArrk=(st)/r=(10xx3)/5=6s=krtk=str=10×35=6

"the equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(s=(6r)/t)color(white)(2/2)|)))

s=3" when "r=4

s=(6r)/t

rArrt=(6r)/s=(6xx4)/3=8