Home / 178.20-245.70-138.78

Finding the Fourth Proportional to 178.20, 245.70 and 138.78

Calculator

Solution

The fourth proportional to 178.20, 245.70 and 138.78 is: 191.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    178.20 : 245.70 = 138.78 : x
  2. Step 2: Convert to fraction form
    178.20/245.70 = 138.78/x
  3. Step 3: Cross multiply
    178.20x = 245.70 × 138.78
  4. Step 4: Simplify right side
    178.20x = 34,098.25
  5. Step 5: Solve for x
    x = 34,098.25/178.20
  6. Step 6: Final answer
    x = 191.35

Related Problems

Find fourth proportional to 89.10, 122.85 and 69.39
Half scale
Find fourth proportional to 356.40, 491.40 and 277.56
Double scale
Find fourth proportional to 179.20, 247.08 and 139.78
Similar ratio
Find fourth proportional to 267.30, 368.55 and 208.17
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.