Home / 206.85-310.40-85.13

Finding the Fourth Proportional to 206.85, 310.40 and 85.13

Calculator

Solution

The fourth proportional to 206.85, 310.40 and 85.13 is: 127.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.85 : 310.40 = 85.13 : x
  2. Step 2: Convert to fraction form
    206.85/310.40 = 85.13/x
  3. Step 3: Cross multiply
    206.85x = 310.40 × 85.13
  4. Step 4: Simplify right side
    206.85x = 26,422.37
  5. Step 5: Solve for x
    x = 26,422.37/206.85
  6. Step 6: Final answer
    x = 127.74

Related Problems

Find fourth proportional to 103.43, 155.20 and 42.56
Half scale
Find fourth proportional to 413.70, 620.79 and 170.25
Double scale
Find fourth proportional to 207.85, 311.90 and 86.13
Similar ratio
Find fourth proportional to 310.28, 465.59 and 127.69
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.