Home / 53.78-80.71-21.31

Finding the Fourth Proportional to 53.78, 80.71 and 21.31

Calculator

Solution

The fourth proportional to 53.78, 80.71 and 21.31 is: 31.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    53.78 : 80.71 = 21.31 : x
  2. Step 2: Convert to fraction form
    53.78/80.71 = 21.31/x
  3. Step 3: Cross multiply
    53.78x = 80.71 × 21.31
  4. Step 4: Simplify right side
    53.78x = 1,719.93
  5. Step 5: Solve for x
    x = 1,719.93/53.78
  6. Step 6: Final answer
    x = 31.98

Related Problems

Find fourth proportional to 26.89, 40.36 and 10.66
Half scale
Find fourth proportional to 107.56, 161.42 and 42.62
Double scale
Find fourth proportional to 54.78, 82.21 and 22.31
Similar ratio
Find fourth proportional to 80.67, 121.07 and 31.97
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.