Home / 31-42.78-19.50

Finding the Fourth Proportional to 31, 42.78 and 19.50

Calculator

Solution

The fourth proportional to 31, 42.78 and 19.50 is: 26.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    31 : 42.78 = 19.50 : x
  2. Step 2: Convert to fraction form
    31/42.78 = 19.50/x
  3. Step 3: Cross multiply
    31x = 42.78 × 19.50
  4. Step 4: Simplify right side
    31x = 834.21
  5. Step 5: Solve for x
    x = 834.21/31
  6. Step 6: Final answer
    x = 26.91

Related Problems

Find fourth proportional to 15.50, 21.39 and 9.75
Half scale
Find fourth proportional to 62, 85.56 and 39
Double scale
Find fourth proportional to 32, 44.16 and 20.50
Similar ratio
Find fourth proportional to 46.50, 64.17 and 29.25
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.