Home / 311.20-429.12-278.40

Finding the Fourth Proportional to 311.20, 429.12 and 278.40

Calculator

Solution

The fourth proportional to 311.20, 429.12 and 278.40 is: 383.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.20 : 429.12 = 278.40 : x
  2. Step 2: Convert to fraction form
    311.20/429.12 = 278.40/x
  3. Step 3: Cross multiply
    311.20x = 429.12 × 278.40
  4. Step 4: Simplify right side
    311.20x = 119,467.01
  5. Step 5: Solve for x
    x = 119,467.01/311.20
  6. Step 6: Final answer
    x = 383.89

Related Problems

Find fourth proportional to 155.60, 214.56 and 139.20
Half scale
Find fourth proportional to 622.40, 858.24 and 556.80
Double scale
Find fourth proportional to 312.20, 430.50 and 279.40
Similar ratio
Find fourth proportional to 466.80, 643.68 and 417.60
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.