Home / 385.90-578.39-212.65

Finding the Fourth Proportional to 385.90, 578.39 and 212.65

Calculator

Solution

The fourth proportional to 385.90, 578.39 and 212.65 is: 318.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    385.90 : 578.39 = 212.65 : x
  2. Step 2: Convert to fraction form
    385.90/578.39 = 212.65/x
  3. Step 3: Cross multiply
    385.90x = 578.39 × 212.65
  4. Step 4: Simplify right side
    385.90x = 122,994.63
  5. Step 5: Solve for x
    x = 122,994.63/385.90
  6. Step 6: Final answer
    x = 318.72

Related Problems

Find fourth proportional to 192.95, 289.20 and 106.33
Half scale
Find fourth proportional to 771.80, 1,156.78 and 425.30
Double scale
Find fourth proportional to 386.90, 579.89 and 213.65
Similar ratio
Find fourth proportional to 578.85, 867.59 and 318.98
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.