Home / 257.55-388.09-212.90

Finding the Fourth Proportional to 257.55, 388.09 and 212.90

Calculator

Solution

The fourth proportional to 257.55, 388.09 and 212.90 is: 320.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.55 : 388.09 = 212.90 : x
  2. Step 2: Convert to fraction form
    257.55/388.09 = 212.90/x
  3. Step 3: Cross multiply
    257.55x = 388.09 × 212.90
  4. Step 4: Simplify right side
    257.55x = 82,621.79
  5. Step 5: Solve for x
    x = 82,621.79/257.55
  6. Step 6: Final answer
    x = 320.80

Related Problems

Find fourth proportional to 128.77, 194.04 and 106.45
Half scale
Find fourth proportional to 515.09, 776.17 and 425.79
Double scale
Find fourth proportional to 258.55, 389.59 and 213.90
Similar ratio
Find fourth proportional to 386.32, 582.13 and 319.34
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.