Home / 680.80-1,021.28-391.84

Finding the Fourth Proportional to 680.80, 1,021.28 and 391.84

Calculator

Solution

The fourth proportional to 680.80, 1,021.28 and 391.84 is: 587.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.80 : 1,021.28 = 391.84 : x
  2. Step 2: Convert to fraction form
    680.80/1,021.28 = 391.84/x
  3. Step 3: Cross multiply
    680.80x = 1,021.28 × 391.84
  4. Step 4: Simplify right side
    680.80x = 400,178.36
  5. Step 5: Solve for x
    x = 400,178.36/680.80
  6. Step 6: Final answer
    x = 587.81

Related Problems

Find fourth proportional to 340.40, 510.64 and 195.92
Half scale
Find fourth proportional to 1,361.60, 2,042.56 and 783.68
Double scale
Find fourth proportional to 681.80, 1,022.78 and 392.84
Similar ratio
Find fourth proportional to 1,021.20, 1,531.92 and 587.76
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.