Home / 145.20-217.68-76.80

Finding the Fourth Proportional to 145.20, 217.68 and 76.80

Calculator

Solution

The fourth proportional to 145.20, 217.68 and 76.80 is: 115.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    145.20 : 217.68 = 76.80 : x
  2. Step 2: Convert to fraction form
    145.20/217.68 = 76.80/x
  3. Step 3: Cross multiply
    145.20x = 217.68 × 76.80
  4. Step 4: Simplify right side
    145.20x = 16,717.82
  5. Step 5: Solve for x
    x = 16,717.82/145.20
  6. Step 6: Final answer
    x = 115.14

Related Problems

Find fourth proportional to 72.60, 108.84 and 38.40
Half scale
Find fourth proportional to 290.40, 435.36 and 153.60
Double scale
Find fourth proportional to 146.20, 219.18 and 77.80
Similar ratio
Find fourth proportional to 217.80, 326.52 and 115.20
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.