Home / 45.25-67.85-20.87

Finding the Fourth Proportional to 45.25, 67.85 and 20.87

Calculator

Solution

The fourth proportional to 45.25, 67.85 and 20.87 is: 31.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    45.25 : 67.85 = 20.87 : x
  2. Step 2: Convert to fraction form
    45.25/67.85 = 20.87/x
  3. Step 3: Cross multiply
    45.25x = 67.85 × 20.87
  4. Step 4: Simplify right side
    45.25x = 1,416.25
  5. Step 5: Solve for x
    x = 1,416.25/45.25
  6. Step 6: Final answer
    x = 31.30

Related Problems

Find fourth proportional to 22.62, 33.93 and 10.44
Half scale
Find fourth proportional to 90.50, 135.71 and 41.75
Double scale
Find fourth proportional to 46.25, 69.35 and 21.87
Similar ratio
Find fourth proportional to 67.87, 101.78 and 31.31
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.