Home / 112.78-169.31-87.11

Finding the Fourth Proportional to 112.78, 169.31 and 87.11

Calculator

Solution

The fourth proportional to 112.78, 169.31 and 87.11 is: 130.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    112.78 : 169.31 = 87.11 : x
  2. Step 2: Convert to fraction form
    112.78/169.31 = 87.11/x
  3. Step 3: Cross multiply
    112.78x = 169.31 × 87.11
  4. Step 4: Simplify right side
    112.78x = 14,748.58
  5. Step 5: Solve for x
    x = 14,748.58/112.78
  6. Step 6: Final answer
    x = 130.78

Related Problems

Find fourth proportional to 56.39, 84.65 and 43.56
Half scale
Find fourth proportional to 225.56, 338.61 and 174.23
Double scale
Find fourth proportional to 113.78, 170.81 and 88.11
Similar ratio
Find fourth proportional to 169.17, 253.96 and 130.67
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.