Home / 659.60-991.80-645.20

Finding the Fourth Proportional to 659.60, 991.80 and 645.20

Calculator

Solution

The fourth proportional to 659.60, 991.80 and 645.20 is: 970.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    659.60 : 991.80 = 645.20 : x
  2. Step 2: Convert to fraction form
    659.60/991.80 = 645.20/x
  3. Step 3: Cross multiply
    659.60x = 991.80 × 645.20
  4. Step 4: Simplify right side
    659.60x = 639,909.36
  5. Step 5: Solve for x
    x = 639,909.36/659.60
  6. Step 6: Final answer
    x = 970.15

Related Problems

Find fourth proportional to 329.80, 495.90 and 322.60
Half scale
Find fourth proportional to 1,319.20, 1,983.60 and 1,290.40
Double scale
Find fourth proportional to 660.60, 993.30 and 646.20
Similar ratio
Find fourth proportional to 989.40, 1,487.70 and 967.80
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.