Home / 811.18-1,218.64-778.40

Finding the Fourth Proportional to 811.18, 1,218.64 and 778.40

Calculator

Solution

The fourth proportional to 811.18, 1,218.64 and 778.40 is: 1,169.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.18 : 1,218.64 = 778.40 : x
  2. Step 2: Convert to fraction form
    811.18/1,218.64 = 778.40/x
  3. Step 3: Cross multiply
    811.18x = 1,218.64 × 778.40
  4. Step 4: Simplify right side
    811.18x = 948,589.38
  5. Step 5: Solve for x
    x = 948,589.38/811.18
  6. Step 6: Final answer
    x = 1,169.39

Related Problems

Find fourth proportional to 405.59, 609.32 and 389.20
Half scale
Find fourth proportional to 1,622.36, 2,437.28 and 1,556.80
Double scale
Find fourth proportional to 812.18, 1,220.14 and 779.40
Similar ratio
Find fourth proportional to 1,216.77, 1,827.96 and 1,167.60
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.