Home / 13.87-20.81-7.86

Finding the Fourth Proportional to 13.87, 20.81 and 7.86

Calculator

Solution

The fourth proportional to 13.87, 20.81 and 7.86 is: 11.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.87 : 20.81 = 7.86 : x
  2. Step 2: Convert to fraction form
    13.87/20.81 = 7.86/x
  3. Step 3: Cross multiply
    13.87x = 20.81 × 7.86
  4. Step 4: Simplify right side
    13.87x = 163.59
  5. Step 5: Solve for x
    x = 163.59/13.87
  6. Step 6: Final answer
    x = 11.80

Related Problems

Find fourth proportional to 6.93, 10.41 and 3.93
Half scale
Find fourth proportional to 27.74, 41.63 and 15.72
Double scale
Find fourth proportional to 14.87, 22.31 and 8.86
Similar ratio
Find fourth proportional to 20.80, 31.22 and 11.79
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.