If y varies directly as x and y = 198 when x = 22, how do you find y when x = 182?

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Answer 1 · 2015-07-04T19:59:19

#y = 1638#

"#y# varies directly as #x#" tells us that for some constant (some number) #k#, we have"

#y = kx#

We are also told that #y = 198# when #x = 22#.

We can use this to find the number #k#.

#198 =k*22# so

#k = 198/22 = (11*18)/(11*2) = 18/2 =9#

So we have learned that #y = 9x#

Now, when #x=182#, we must have #y = 9(182)#
So
#y = 1638#

Answer 2 · 2015-07-04T20:34:09

You can use cross multiplication.

#y_1/x_1=y_2/x_2#, where #y_1=198;# #x_1=22;# #y_2=?;# #x_2=182#.

#198/22=y_2/182#

Cross multiply.

#(198*182)/(22)=y_2#

#1368=y_2#

Switch sides.

#y_2=1368#