Home / 771.20-1,156.80-686.15

Finding the Fourth Proportional to 771.20, 1,156.80 and 686.15

Calculator

Solution

The fourth proportional to 771.20, 1,156.80 and 686.15 is: 1,029.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    771.20 : 1,156.80 = 686.15 : x
  2. Step 2: Convert to fraction form
    771.20/1,156.80 = 686.15/x
  3. Step 3: Cross multiply
    771.20x = 1,156.80 × 686.15
  4. Step 4: Simplify right side
    771.20x = 793,738.32
  5. Step 5: Solve for x
    x = 793,738.32/771.20
  6. Step 6: Final answer
    x = 1,029.23

Related Problems

Find fourth proportional to 385.60, 578.40 and 343.08
Half scale
Find fourth proportional to 1,542.40, 2,313.60 and 1,372.30
Double scale
Find fourth proportional to 772.20, 1,158.30 and 687.15
Similar ratio
Find fourth proportional to 1,156.80, 1,735.20 and 1,029.23
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.