Home / 345.12-517.80-128.76

Finding the Fourth Proportional to 345.12, 517.80 and 128.76

Calculator

Solution

The fourth proportional to 345.12, 517.80 and 128.76 is: 193.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    345.12 : 517.80 = 128.76 : x
  2. Step 2: Convert to fraction form
    345.12/517.80 = 128.76/x
  3. Step 3: Cross multiply
    345.12x = 517.80 × 128.76
  4. Step 4: Simplify right side
    345.12x = 66,671.93
  5. Step 5: Solve for x
    x = 66,671.93/345.12
  6. Step 6: Final answer
    x = 193.18

Related Problems

Find fourth proportional to 172.56, 258.90 and 64.38
Half scale
Find fourth proportional to 690.24, 1,035.60 and 257.52
Double scale
Find fourth proportional to 346.12, 519.30 and 129.76
Similar ratio
Find fourth proportional to 517.68, 776.70 and 193.14
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.