Home / 57.21-78.91-39.69

Finding the Fourth Proportional to 57.21, 78.91 and 39.69

Calculator

Solution

The fourth proportional to 57.21, 78.91 and 39.69 is: 54.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.21 : 78.91 = 39.69 : x
  2. Step 2: Convert to fraction form
    57.21/78.91 = 39.69/x
  3. Step 3: Cross multiply
    57.21x = 78.91 × 39.69
  4. Step 4: Simplify right side
    57.21x = 3,131.94
  5. Step 5: Solve for x
    x = 3,131.94/57.21
  6. Step 6: Final answer
    x = 54.74

Related Problems

Find fourth proportional to 28.61, 39.46 and 19.85
Half scale
Find fourth proportional to 114.42, 157.82 and 79.38
Double scale
Find fourth proportional to 58.21, 80.29 and 40.69
Similar ratio
Find fourth proportional to 85.82, 118.37 and 59.54
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.