Percentage · Set 1

Read the formula sheet first, then work through the 15 questions below. Each answer comes with a step-by-step solution — read it even when you get the question right, the shortcut is often faster than your method.

Formula sheet

• x% of y = xy/100; x% = x/100.
• Fraction ↔ % : 1/2=50, 1/3=33⅓, 1/4=25, 1/5=20, 1/6=16⅔, 1/7=14²⁄₇, 1/8=12.5, 1/9=11⅑, 1/10=10, 1/11=9 1/11, 1/12=8⅓.
• % change = (change / original) × 100.
• If A is R% more than B, B is R/(100+R) × 100 % less than A. If A is R% less than B, B is R/(100−R) × 100 % more than A.
• Successive changes a% and b%: net = a + b + ab/100 (use − for decrease).
• Price up by R% → to keep expenditure same, cut consumption by R/(100+R)×100 %.
• Population after n years at r%: P(1 + r/100)ⁿ.

Practice

Pick an answer to see whether it is right and the worked solution. Your score is saved when you finish the set.