Home / 217.29-299.85-128.76

Finding the Fourth Proportional to 217.29, 299.85 and 128.76

Calculator

Solution

The fourth proportional to 217.29, 299.85 and 128.76 is: 177.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    217.29 : 299.85 = 128.76 : x
  2. Step 2: Convert to fraction form
    217.29/299.85 = 128.76/x
  3. Step 3: Cross multiply
    217.29x = 299.85 × 128.76
  4. Step 4: Simplify right side
    217.29x = 38,608.69
  5. Step 5: Solve for x
    x = 38,608.69/217.29
  6. Step 6: Final answer
    x = 177.68

Related Problems

Find fourth proportional to 108.65, 149.93 and 64.38
Half scale
Find fourth proportional to 434.58, 599.70 and 257.52
Double scale
Find fourth proportional to 218.29, 301.23 and 129.76
Similar ratio
Find fourth proportional to 325.94, 449.78 and 193.14
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.