Home / 252.21-378.30-81.21

Finding the Fourth Proportional to 252.21, 378.30 and 81.21

Calculator

Solution

The fourth proportional to 252.21, 378.30 and 81.21 is: 121.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    252.21 : 378.30 = 81.21 : x
  2. Step 2: Convert to fraction form
    252.21/378.30 = 81.21/x
  3. Step 3: Cross multiply
    252.21x = 378.30 × 81.21
  4. Step 4: Simplify right side
    252.21x = 30,721.74
  5. Step 5: Solve for x
    x = 30,721.74/252.21
  6. Step 6: Final answer
    x = 121.81

Related Problems

Find fourth proportional to 126.11, 189.15 and 40.61
Half scale
Find fourth proportional to 504.42, 756.60 and 162.42
Double scale
Find fourth proportional to 253.21, 379.80 and 82.21
Similar ratio
Find fourth proportional to 378.32, 567.45 and 121.82
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.