Home / 19.81-27.31-12.91

Finding the Fourth Proportional to 19.81, 27.31 and 12.91

Calculator

Solution

The fourth proportional to 19.81, 27.31 and 12.91 is: 17.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.81 : 27.31 = 12.91 : x
  2. Step 2: Convert to fraction form
    19.81/27.31 = 12.91/x
  3. Step 3: Cross multiply
    19.81x = 27.31 × 12.91
  4. Step 4: Simplify right side
    19.81x = 352.57
  5. Step 5: Solve for x
    x = 352.57/19.81
  6. Step 6: Final answer
    x = 17.80

Related Problems

Find fourth proportional to 9.91, 13.66 and 6.46
Half scale
Find fourth proportional to 39.62, 54.62 and 25.82
Double scale
Find fourth proportional to 20.81, 28.69 and 13.91
Similar ratio
Find fourth proportional to 29.72, 40.97 and 19.37
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.