Question

An oil drilling company is drilling a hole. The elevation of the bottom of the hole changes by feet each day. After a certain number of days, the bottom of the hole is at an elevation of feet. Which equation can be used to find x, the number of days they drilled?

Answer 1

option.D

Explanation:

• each day it changes by
  `-73(1)/(4)`

• so for two days , the elevation becomes
  `-73(1)/(4)` +
  `-73(1)/(4)`

• for 3 days :
  `-73(1)/(4)` +
  `-73(1)/(4)` +
  `-73(1)/(4)`

• so, for n days,
  `-73(1)/(4)` + ........ n times

= n*
`-73(1)/(4)`

• therefore, for x days, elevation = x*
  `-73(1)/(4)`

• as it is given that after certain days this elevation has reached
  `-366(1)/(4)`

• so, x*
  `-73(1)/(4)` =
  `-366(1)/(4)`