Question

A snail moves at the speed of 76 millimeters per minute. Nancy writes the following steps to calculate this speed in centimeters/hour (cm/h).

[1 millimeter = 0.1 centimeter]

Step 1: Multiply 76 by 0.1.
Step 2: Multiply the result obtained in step 1 by 60.
Step 3: Multiply the result obtained in step 2 by 60.
Step 4: Write the answer with the unit cm/h.

Which step is incorrect in the conversion?

Answer 1

The step 3 is incorrect in the conversion, is not necessary

Explanation:

we have

The speed is
`76(mm)/(min)`

we know that

1 mm=0.1 cm

1 min=1/60 h

so

`76(mm)/(min)=76(0.1)/(1/60)=76(0.1)(60)=456(cm)/(h)`

step 1

Multiply 76 by 0.1

`76(0.1)=7.6`

The step 1 is correct

step 2

Multiply the result obtained in step 1 by 60.

`7.6(60)=456`

The step 2 is correct

step 3

Multiply the result obtained in step 2 by 60

This step is not correct

therefore

The step 3 is incorrect in the conversion, is not necessary