Home / 658.40-987.78-398.68

Finding the Fourth Proportional to 658.40, 987.78 and 398.68

Calculator

Solution

The fourth proportional to 658.40, 987.78 and 398.68 is: 598.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    658.40 : 987.78 = 398.68 : x
  2. Step 2: Convert to fraction form
    658.40/987.78 = 398.68/x
  3. Step 3: Cross multiply
    658.40x = 987.78 × 398.68
  4. Step 4: Simplify right side
    658.40x = 393,808.13
  5. Step 5: Solve for x
    x = 393,808.13/658.40
  6. Step 6: Final answer
    x = 598.13

Related Problems

Find fourth proportional to 329.20, 493.89 and 199.34
Half scale
Find fourth proportional to 1,316.80, 1,975.56 and 797.36
Double scale
Find fourth proportional to 659.40, 989.28 and 399.68
Similar ratio
Find fourth proportional to 987.60, 1,481.67 and 598.02
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.