Home / 656.47-905.79-390.99

Finding the Fourth Proportional to 656.47, 905.79 and 390.99

Calculator

Solution

The fourth proportional to 656.47, 905.79 and 390.99 is: 539.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    656.47 : 905.79 = 390.99 : x
  2. Step 2: Convert to fraction form
    656.47/905.79 = 390.99/x
  3. Step 3: Cross multiply
    656.47x = 905.79 × 390.99
  4. Step 4: Simplify right side
    656.47x = 354,154.83
  5. Step 5: Solve for x
    x = 354,154.83/656.47
  6. Step 6: Final answer
    x = 539.48

Related Problems

Find fourth proportional to 328.24, 452.90 and 195.50
Half scale
Find fourth proportional to 1,312.94, 1,811.58 and 781.98
Double scale
Find fourth proportional to 657.47, 907.17 and 391.99
Similar ratio
Find fourth proportional to 984.71, 1,358.69 and 586.49
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.