We have
         Â
It is given that 200 < T < 300
or                 200 < 30 + 25(x - 3) < 300
or                  170 < 25 (x - 3) < 270
or               Â
or              6.8 + 3 < x < 10.8 + 3
or                 9.8 < x < 13.8
 Hence, the depth will be between 9.8 km and 13.8 km.
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