Page 133 - Maths Skills - 8

Comparing Quantities 131

MIND MAP

Comparing Quantities Interest

Conversions

% as a Fraction
29 Simple Interest Compound Interest
e.g. 29% =
100 Principal × Rate × Time 1. When the Interest is Compounded
% as a Ratio 100 Annually
25 1
e.g. 25% = = = 1:4 R n
100 4 A = P 1 +
Ratio into % 100
1 1 A Amount
e.g. 1:4 = = × 100% = 25%
4 4 P Principal
% as a Decimal n Time in year
75 Profit and Loss R Rate
e.g. 75% = = 0.75 C. I. = A – P
100 Profit
Decimal into % S.P. > C.P. 2. When the Interest is Compounded
e.g. 0.35 = 0.35 × 100% = 35% Half-Yearly
Profit = S.P. – C.P. In above formula
Profit × 100
Profit % = ⇒ n becomes two times
C.P. ⇒ R becomes half
Loss 3. When the Interest is Compounded
S.P. < C.P. Quarterly
Loss = C.P. – S.P. In above formula
Loss × 100 ⇒ n becomes four times
Loss % =
C.P. 1
⇒ R becomes
4
4. When Rate of Interest for
Discount Successive Years are Different

� Discount = Market Price (M.P.) – Selling Price (S.P.) A= P1+ a 1+ b 1+ c

Discount 100 100 100
� Discount % = × 100%
Marked Price Where a, b, c are rate of interest for
successive years
� Discount is always calculated on the marked price
of the article