Home / 208.42-312.63-86.65

Finding the Fourth Proportional to 208.42, 312.63 and 86.65

Calculator

Solution

The fourth proportional to 208.42, 312.63 and 86.65 is: 129.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.42 : 312.63 = 86.65 : x
  2. Step 2: Convert to fraction form
    208.42/312.63 = 86.65/x
  3. Step 3: Cross multiply
    208.42x = 312.63 × 86.65
  4. Step 4: Simplify right side
    208.42x = 27,088.28
  5. Step 5: Solve for x
    x = 27,088.28/208.42
  6. Step 6: Final answer
    x = 129.97

Related Problems

Find fourth proportional to 104.21, 156.31 and 43.32
Half scale
Find fourth proportional to 416.84, 625.25 and 173.30
Double scale
Find fourth proportional to 209.42, 314.13 and 87.65
Similar ratio
Find fourth proportional to 312.63, 468.94 and 129.97
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.