Home / 256-384-85

Finding the Fourth Proportional to 256, 384 and 85

Calculator

Solution

The fourth proportional to 256, 384 and 85 is: 127.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    256 : 384 = 85 : x
  2. Step 2: Convert to fraction form
    256/384 = 85/x
  3. Step 3: Cross multiply
    256x = 384 × 85
  4. Step 4: Simplify right side
    256x = 32,640
  5. Step 5: Solve for x
    x = 32,640/256
  6. Step 6: Final answer
    x = 127.50

Related Problems

Find fourth proportional to 128, 192 and 42.50
Half scale
Find fourth proportional to 512, 768 and 170
Double scale
Find fourth proportional to 257, 385.50 and 86
Similar ratio
Find fourth proportional to 384, 576 and 127.50
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.