Home / 47.80-71.70-39.80

Finding the Fourth Proportional to 47.80, 71.70 and 39.80

Calculator

Solution

The fourth proportional to 47.80, 71.70 and 39.80 is: 59.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.80 : 71.70 = 39.80 : x
  2. Step 2: Convert to fraction form
    47.80/71.70 = 39.80/x
  3. Step 3: Cross multiply
    47.80x = 71.70 × 39.80
  4. Step 4: Simplify right side
    47.80x = 2,853.66
  5. Step 5: Solve for x
    x = 2,853.66/47.80
  6. Step 6: Final answer
    x = 59.70

Related Problems

Find fourth proportional to 23.90, 35.85 and 19.90
Half scale
Find fourth proportional to 95.60, 143.40 and 79.60
Double scale
Find fourth proportional to 48.80, 73.20 and 40.80
Similar ratio
Find fourth proportional to 71.70, 107.55 and 59.70
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.