Home / 71.87-107.80-20.51

Finding the Fourth Proportional to 71.87, 107.80 and 20.51

Calculator

Solution

The fourth proportional to 71.87, 107.80 and 20.51 is: 30.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.87 : 107.80 = 20.51 : x
  2. Step 2: Convert to fraction form
    71.87/107.80 = 20.51/x
  3. Step 3: Cross multiply
    71.87x = 107.80 × 20.51
  4. Step 4: Simplify right side
    71.87x = 2,210.98
  5. Step 5: Solve for x
    x = 2,210.98/71.87
  6. Step 6: Final answer
    x = 30.76

Related Problems

Find fourth proportional to 35.94, 53.90 and 10.26
Half scale
Find fourth proportional to 143.74, 215.60 and 41.02
Double scale
Find fourth proportional to 72.87, 109.30 and 21.51
Similar ratio
Find fourth proportional to 107.81, 161.70 and 30.77
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.