Home / 645.28-891.28-499.68

Finding the Fourth Proportional to 645.28, 891.28 and 499.68

Calculator

Solution

The fourth proportional to 645.28, 891.28 and 499.68 is: 690.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.28 : 891.28 = 499.68 : x
  2. Step 2: Convert to fraction form
    645.28/891.28 = 499.68/x
  3. Step 3: Cross multiply
    645.28x = 891.28 × 499.68
  4. Step 4: Simplify right side
    645.28x = 445,354.79
  5. Step 5: Solve for x
    x = 445,354.79/645.28
  6. Step 6: Final answer
    x = 690.17

Related Problems

Find fourth proportional to 322.64, 445.64 and 249.84
Half scale
Find fourth proportional to 1,290.56, 1,782.56 and 999.36
Double scale
Find fourth proportional to 646.28, 892.66 and 500.68
Similar ratio
Find fourth proportional to 967.92, 1,336.92 and 749.52
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.