Question 263 of 480
What is the decimal equivalent of the fraction 7/16, rounded to three significant figures?
Correct Answer:
B
Explanation
To find the decimal equivalent of the fraction \( \frac{7}{16} \) and round it to three significant figures, we will follow a systematic approach.
### Step 1: Convert the Fraction to Decimal
To convert the fraction \( \frac{7}{16} \) into a decimal, we can perform the division of 7 by 16.
1. **Long Division Method**:
- Divide 7 by 16.
- Since 7 is less than 16, we start with 0.
- We can add a decimal point and a zero to 7, making it 70.
- Now, divide 70 by 16:
- 16 goes into 70 four times (since \( 16 \times 4 = 64 \)).
- Subtract 64 from 70, which gives us 6.
- Bring down another 0, making it 60.
- 16 goes into 60 three times (since \( 16 \times 3 = 48 \)).
- Subtract 48 from 60, which gives us 12.
- Bring down another 0, making it 120.
- 16 goes into 120 seven times (since \( 16 \times 7 = 112 \)).
- Subtract 112 from 120, which gives us 8.
- Bring down another 0, making it 80.
- 16 goes into 80 five times (since \( 16 \times 5 = 80 \)).
- Subtract 80 from 80, which gives us 0.
So, the long division gives us:
\[
\frac{7}{16} = 0.4375
\]
### Step 2: Rounding to Three Significant Figures
Now that we have the decimal \( 0.4375 \), we need to round it to three significant figures.
1. **Identifying Significant Figures**:
- The first three significant figures in \( 0.4375 \) are 4, 3, and 7.
- The next digit (the fourth significant figure) is 5.
2. **Rounding Rule**:
- If the digit following the last significant figure (in this case, 7) is 5 or greater, we round up the last significant figure.
- Since the fourth digit is 5, we round up the 7 to 8.
Thus, rounding \( 0.4375 \) to three significant figures gives us:
\[
0.438
\]
### Conclusion: Correct Option
The correct option is **B. 0.438**.
### Explanation of Other Options
- **Option A: 0.437**: This option is incorrect because it does not round up the last significant figure (7) when the next digit (5) indicates that it should be rounded up.
- **Option C: 0.439**: This option is incorrect because it incorrectly rounds the last significant figure (7) to 9 instead of 8.
- **Option D: 0.440**: This option is incorrect because it rounds the last significant figure (7) to 0, which is not accurate based on the rounding rules.
### Revision Summary
- To convert a fraction to a decimal, perform long division.
- Identify significant figures correctly when rounding.
- Apply rounding rules: round up if the next digit is 5 or greater.
- The decimal equivalent of \( \frac{7}{16} \) rounded to three significant figures is \( 0.438 \).