Home / 687.78-949.17-393.09

Finding the Fourth Proportional to 687.78, 949.17 and 393.09

Calculator

Solution

The fourth proportional to 687.78, 949.17 and 393.09 is: 542.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.78 : 949.17 = 393.09 : x
  2. Step 2: Convert to fraction form
    687.78/949.17 = 393.09/x
  3. Step 3: Cross multiply
    687.78x = 949.17 × 393.09
  4. Step 4: Simplify right side
    687.78x = 373,109.24
  5. Step 5: Solve for x
    x = 373,109.24/687.78
  6. Step 6: Final answer
    x = 542.48

Related Problems

Find fourth proportional to 343.89, 474.59 and 196.55
Half scale
Find fourth proportional to 1,375.56, 1,898.34 and 786.18
Double scale
Find fourth proportional to 688.78, 950.55 and 394.09
Similar ratio
Find fourth proportional to 1,031.67, 1,423.76 and 589.64
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.