Home / 645.30-890.19-478.98

Finding the Fourth Proportional to 645.30, 890.19 and 478.98

Calculator

Solution

The fourth proportional to 645.30, 890.19 and 478.98 is: 660.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.30 : 890.19 = 478.98 : x
  2. Step 2: Convert to fraction form
    645.30/890.19 = 478.98/x
  3. Step 3: Cross multiply
    645.30x = 890.19 × 478.98
  4. Step 4: Simplify right side
    645.30x = 426,383.21
  5. Step 5: Solve for x
    x = 426,383.21/645.30
  6. Step 6: Final answer
    x = 660.75

Related Problems

Find fourth proportional to 322.65, 445.10 and 239.49
Half scale
Find fourth proportional to 1,290.60, 1,780.38 and 957.96
Double scale
Find fourth proportional to 646.30, 891.57 and 479.98
Similar ratio
Find fourth proportional to 967.95, 1,335.29 and 718.47
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.