Home / 785.80-1,178.70-421.30

Finding the Fourth Proportional to 785.80, 1,178.70 and 421.30

Calculator

Solution

The fourth proportional to 785.80, 1,178.70 and 421.30 is: 631.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.80 : 1,178.70 = 421.30 : x
  2. Step 2: Convert to fraction form
    785.80/1,178.70 = 421.30/x
  3. Step 3: Cross multiply
    785.80x = 1,178.70 × 421.30
  4. Step 4: Simplify right side
    785.80x = 496,586.31
  5. Step 5: Solve for x
    x = 496,586.31/785.80
  6. Step 6: Final answer
    x = 631.95

Related Problems

Find fourth proportional to 392.90, 589.35 and 210.65
Half scale
Find fourth proportional to 1,571.60, 2,357.40 and 842.60
Double scale
Find fourth proportional to 786.80, 1,180.20 and 422.30
Similar ratio
Find fourth proportional to 1,178.70, 1,768.05 and 631.95
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.