Home / 101.78-140.55-81.20

Finding the Fourth Proportional to 101.78, 140.55 and 81.20

Calculator

Solution

The fourth proportional to 101.78, 140.55 and 81.20 is: 112.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.78 : 140.55 = 81.20 : x
  2. Step 2: Convert to fraction form
    101.78/140.55 = 81.20/x
  3. Step 3: Cross multiply
    101.78x = 140.55 × 81.20
  4. Step 4: Simplify right side
    101.78x = 11,411.96
  5. Step 5: Solve for x
    x = 11,411.96/101.78
  6. Step 6: Final answer
    x = 112.13

Related Problems

Find fourth proportional to 50.89, 70.28 and 40.60
Half scale
Find fourth proportional to 203.55, 281.10 and 162.39
Double scale
Find fourth proportional to 102.78, 141.93 and 82.20
Similar ratio
Find fourth proportional to 152.66, 210.83 and 121.79
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.