Home / 215.78-297.88-138.20

Finding the Fourth Proportional to 215.78, 297.88 and 138.20

Calculator

Solution

The fourth proportional to 215.78, 297.88 and 138.20 is: 190.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.78 : 297.88 = 138.20 : x
  2. Step 2: Convert to fraction form
    215.78/297.88 = 138.20/x
  3. Step 3: Cross multiply
    215.78x = 297.88 × 138.20
  4. Step 4: Simplify right side
    215.78x = 41,166.33
  5. Step 5: Solve for x
    x = 41,166.33/215.78
  6. Step 6: Final answer
    x = 190.78

Related Problems

Find fourth proportional to 107.89, 148.94 and 69.10
Half scale
Find fourth proportional to 431.56, 595.75 and 276.40
Double scale
Find fourth proportional to 216.78, 299.26 and 139.20
Similar ratio
Find fourth proportional to 323.67, 446.81 and 207.30
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.