Home / 809.76-1,214.40-679.80

Finding the Fourth Proportional to 809.76, 1,214.40 and 679.80

Calculator

Solution

The fourth proportional to 809.76, 1,214.40 and 679.80 is: 1,019.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.76 : 1,214.40 = 679.80 : x
  2. Step 2: Convert to fraction form
    809.76/1,214.40 = 679.80/x
  3. Step 3: Cross multiply
    809.76x = 1,214.40 × 679.80
  4. Step 4: Simplify right side
    809.76x = 825,549.12
  5. Step 5: Solve for x
    x = 825,549.12/809.76
  6. Step 6: Final answer
    x = 1,019.50

Related Problems

Find fourth proportional to 404.88, 607.20 and 339.90
Half scale
Find fourth proportional to 1,619.52, 2,428.80 and 1,359.60
Double scale
Find fourth proportional to 810.76, 1,215.90 and 680.80
Similar ratio
Find fourth proportional to 1,214.64, 1,821.60 and 1,019.70
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.