Home / 665.20-915.56-478.40

Finding the Fourth Proportional to 665.20, 915.56 and 478.40

Calculator

Solution

The fourth proportional to 665.20, 915.56 and 478.40 is: 658.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.20 : 915.56 = 478.40 : x
  2. Step 2: Convert to fraction form
    665.20/915.56 = 478.40/x
  3. Step 3: Cross multiply
    665.20x = 915.56 × 478.40
  4. Step 4: Simplify right side
    665.20x = 438,003.90
  5. Step 5: Solve for x
    x = 438,003.90/665.20
  6. Step 6: Final answer
    x = 658.45

Related Problems

Find fourth proportional to 332.60, 457.78 and 239.20
Half scale
Find fourth proportional to 1,330.40, 1,831.12 and 956.80
Double scale
Find fourth proportional to 666.20, 916.94 and 479.40
Similar ratio
Find fourth proportional to 997.80, 1,373.34 and 717.60
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.