What approximate value will come in place of questions mark (?) in the following questions?
`sqrt(3949)xxsqrt(1220)-:sqrt(280)=?`

Options

A. 120
B. 130
C. 140
D. 150

Answer

To solve the expression \( \sqrt{3949} \times \sqrt{1220} \div \sqrt{280} = ? \), we can follow these steps:

### Step 1: Approximate \( \sqrt{3949} \)
To find \( \sqrt{3949} \), we look for perfect squares near 3949. The perfect square closest to 3949 is \( 63^2 = 3969 \). Thus, we can approximate:
\[ \sqrt{3949} \approx 63 \]

### Step 2: Approximate \( \sqrt{1220} \)
Next, we approximate \( \sqrt{1220} \). The perfect square closest to 1220 is \( 35^2 = 1225 \). Therefore, we can approximate:
\[ \sqrt{1220} \approx 35 \]

### Step 3: Approximate \( \sqrt{280} \)
Now, we find \( \sqrt{280} \). The perfect square closest to 280 is \( 17^2 = 289 \). Thus, we can approximate:
\[ \sqrt{280} \approx 17 \]

### Step 4: Substitute the approximations into the expression
Now we substitute the approximated values back into the expression:
\[ \sqrt{3949} \times \sqrt{1220} \div \sqrt{280} \approx 63 \times 35 \div 17 \]

### Step 5: Calculate the multiplication and division
First, calculate \( 63 \times 35 \):
\[ 63 \times 35 = 2205 \]
Now divide by 17:
\[ 2205 \div 17 \approx 129.12 \]

### Step 6: Round to the nearest whole number
Since we are looking for an approximate value, we can round 129.12 to:
\[ ? \approx 129 \]

### Final Answer
The approximate value that comes in place of the question mark (?) is:
\[ \boxed{129} \]