If the thickness of the cover page of a book is `15mu`. If it is represented in mm then find it in significant figure.

Options

A. 4
B. 5
C. 2
D. 3

Explanation

To solve the problem of converting the thickness of the cover page of a book from micrometers (µm) to millimeters (mm) while considering significant figures, follow these steps:

### Step 1: Understand the given value
The thickness of the cover page is given as 15 µm.

### Step 2: Convert micrometers to millimeters
We know that:
1 µm = \(10^{-3}\) mm

To convert 15 µm to mm, we can use the conversion factor:
\[ 15 \, \mu m = 15 \times 10^{-3} \, mm \]

### Step 3: Perform the multiplication
Calculating the above expression gives:
\[ 15 \times 10^{-3} = 0.015 \, mm \]

### Step 4: Determine significant figures
The original measurement of 15 µm has 2 significant figures (the digits 1 and 5). When converting to mm, the number of significant figures in the result should match the number of significant figures in the original measurement. Therefore, the result in mm should also have 2 significant figures.

### Step 5: Express the final answer
The final answer, maintaining 2 significant figures, is:
\[ 0.015 \, mm \]

### Summary of the solution:
The thickness of the cover page of the book in millimeters, represented with the correct significant figures, is 0.015 mm.

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