Question

# Lara completed 105 sit-ups in 3 minutes. She can 420 sit-ups at the same rate in ____________ minutes.

- 10
- 11
- 14
- 12

Hint:

### The unitary method is a technique for solving a problem by first finding the value of a single unit, and then finding the necessary value by multiplying the single unit value.

## The correct answer is: 12

### Here, it is given that Lara completed 105 sit-ups in 3 minutes. We have to find the time required to do 420 sit-ups.

We have, time required to do 105 sit- ups = 3 minutes.

Time required to do 1 sit-up = 3/105 minutes.

So, time required to do 420 sit-ups = 3⁄105 × 420 = 12 minutes.

Hence, the correct option is D.

We can find the time required to 420 sit ups by multiplying the time required to 105 sit ups by 4.

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