Home / 54.49-81.72-19.78

Finding the Fourth Proportional to 54.49, 81.72 and 19.78

Calculator

Solution

The fourth proportional to 54.49, 81.72 and 19.78 is: 29.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    54.49 : 81.72 = 19.78 : x
  2. Step 2: Convert to fraction form
    54.49/81.72 = 19.78/x
  3. Step 3: Cross multiply
    54.49x = 81.72 × 19.78
  4. Step 4: Simplify right side
    54.49x = 1,616.42
  5. Step 5: Solve for x
    x = 1,616.42/54.49
  6. Step 6: Final answer
    x = 29.66

Related Problems

Find fourth proportional to 27.25, 40.86 and 9.89
Half scale
Find fourth proportional to 108.98, 163.44 and 39.56
Double scale
Find fourth proportional to 55.49, 83.22 and 20.78
Similar ratio
Find fourth proportional to 81.74, 122.58 and 29.67
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.