Home / 154.91-213.79-99.78

Finding the Fourth Proportional to 154.91, 213.79 and 99.78

Calculator

Solution

The fourth proportional to 154.91, 213.79 and 99.78 is: 137.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    154.91 : 213.79 = 99.78 : x
  2. Step 2: Convert to fraction form
    154.91/213.79 = 99.78/x
  3. Step 3: Cross multiply
    154.91x = 213.79 × 99.78
  4. Step 4: Simplify right side
    154.91x = 21,332.30
  5. Step 5: Solve for x
    x = 21,332.30/154.91
  6. Step 6: Final answer
    x = 137.71

Related Problems

Find fourth proportional to 77.46, 106.89 and 49.89
Half scale
Find fourth proportional to 309.83, 427.58 and 199.56
Double scale
Find fourth proportional to 155.91, 215.17 and 100.78
Similar ratio
Find fourth proportional to 232.37, 320.68 and 149.67
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.