Home / 778.80-1,076.29-638.70

Finding the Fourth Proportional to 778.80, 1,076.29 and 638.70

Calculator

Solution

The fourth proportional to 778.80, 1,076.29 and 638.70 is: 882.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    778.80 : 1,076.29 = 638.70 : x
  2. Step 2: Convert to fraction form
    778.80/1,076.29 = 638.70/x
  3. Step 3: Cross multiply
    778.80x = 1,076.29 × 638.70
  4. Step 4: Simplify right side
    778.80x = 687,426.42
  5. Step 5: Solve for x
    x = 687,426.42/778.80
  6. Step 6: Final answer
    x = 882.67

Related Problems

Find fourth proportional to 389.40, 538.15 and 319.35
Half scale
Find fourth proportional to 1,557.60, 2,152.58 and 1,277.40
Double scale
Find fourth proportional to 779.80, 1,077.67 and 639.70
Similar ratio
Find fourth proportional to 1,168.20, 1,614.44 and 958.05
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.