Home / 103.85-155.76-78.21

Finding the Fourth Proportional to 103.85, 155.76 and 78.21

Calculator

Solution

The fourth proportional to 103.85, 155.76 and 78.21 is: 117.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.85 : 155.76 = 78.21 : x
  2. Step 2: Convert to fraction form
    103.85/155.76 = 78.21/x
  3. Step 3: Cross multiply
    103.85x = 155.76 × 78.21
  4. Step 4: Simplify right side
    103.85x = 12,182.38
  5. Step 5: Solve for x
    x = 12,182.38/103.85
  6. Step 6: Final answer
    x = 117.30

Related Problems

Find fourth proportional to 51.93, 77.88 and 39.11
Half scale
Find fourth proportional to 207.71, 311.52 and 156.43
Double scale
Find fourth proportional to 104.85, 157.26 and 79.21
Similar ratio
Find fourth proportional to 155.78, 233.64 and 117.32
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.