Home / 61-84.20-39.20

Finding the Fourth Proportional to 61, 84.20 and 39.20

Calculator

Solution

The fourth proportional to 61, 84.20 and 39.20 is: 54.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    61 : 84.20 = 39.20 : x
  2. Step 2: Convert to fraction form
    61/84.20 = 39.20/x
  3. Step 3: Cross multiply
    61x = 84.20 × 39.20
  4. Step 4: Simplify right side
    61x = 3,300.64
  5. Step 5: Solve for x
    x = 3,300.64/61
  6. Step 6: Final answer
    x = 54.11

Related Problems

Find fourth proportional to 30.50, 42.10 and 19.60
Half scale
Find fourth proportional to 122, 168.40 and 78.40
Double scale
Find fourth proportional to 62, 85.58 and 40.20
Similar ratio
Find fourth proportional to 91.50, 126.30 and 58.80
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.