Home / 658.20-987.30-640.20

Finding the Fourth Proportional to 658.20, 987.30 and 640.20

Calculator

Solution

The fourth proportional to 658.20, 987.30 and 640.20 is: 960.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    658.20 : 987.30 = 640.20 : x
  2. Step 2: Convert to fraction form
    658.20/987.30 = 640.20/x
  3. Step 3: Cross multiply
    658.20x = 987.30 × 640.20
  4. Step 4: Simplify right side
    658.20x = 632,069.46
  5. Step 5: Solve for x
    x = 632,069.46/658.20
  6. Step 6: Final answer
    x = 960.30

Related Problems

Find fourth proportional to 329.10, 493.65 and 320.10
Half scale
Find fourth proportional to 1,316.40, 1,974.60 and 1,280.40
Double scale
Find fourth proportional to 659.20, 988.80 and 641.20
Similar ratio
Find fourth proportional to 987.30, 1,480.95 and 960.30
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.