Home / 938.80-1,407.12-390.70

Finding the Fourth Proportional to 938.80, 1,407.12 and 390.70

Calculator

Solution

The fourth proportional to 938.80, 1,407.12 and 390.70 is: 585.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.80 : 1,407.12 = 390.70 : x
  2. Step 2: Convert to fraction form
    938.80/1,407.12 = 390.70/x
  3. Step 3: Cross multiply
    938.80x = 1,407.12 × 390.70
  4. Step 4: Simplify right side
    938.80x = 549,761.78
  5. Step 5: Solve for x
    x = 549,761.78/938.80
  6. Step 6: Final answer
    x = 585.60

Related Problems

Find fourth proportional to 469.40, 703.56 and 195.35
Half scale
Find fourth proportional to 1,877.60, 2,814.24 and 781.40
Double scale
Find fourth proportional to 939.80, 1,408.62 and 391.70
Similar ratio
Find fourth proportional to 1,408.20, 2,110.68 and 586.05
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.