Here’s and example of a **SMART MATH** problem for **RATIO PROPORTION.**

**Problem**

**Problem**

A tank normally filled in 8 hours takes 2 hours longer owing to a leak. If the tank is full the leak shall empty in _________ hours?

- 16
- 20
- 25
- 40
- 45

**The Usual Method**

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It takes 8 hours for the tank to be filled, so of the tank will be filled in 1 hour.

Owing to the leak, the tank is filled in 8 + 2 = 10 hours, so of the tank will be filled in 1 hour.

Let the leak empty the tank in ‘*x*’ hours, so of the tank will be emptied in 1 hour.

hours.

**(Ans: 4)**

*Estimated Time to arrive at the answer = 45 seconds.*

**Using Technique**

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Since tank is filled in 1 hour by the inlet working alone and of the tank is filled in 1 hour by keeping both the inlet and the leak open, the time needed for the outlet to empty the tank should be both a multiple of 8 and 10. (Note: and ) The only option satisfying this criteria is option ‘4’.

**(Ans: 4)**

*Estimated Time to arrive at the answer = 10 seconds.*

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