Page 138 - Start Up Mathematics_7

At a Glance

a
1. Ratio of any two non-zero numbers a and b is equal to .
b
2. Four numbers a, b, c and d are said to be in proportion, if the product of the means is equal
to the product of the extremes,
a c
i.e., = ⇒ a × d = b × c
d
b
extremes means
x
3. Percent means per hundred. It is represented by the symbol %, i.e., x% = .
100
4. To convert fractions to percentages, we multiply the fraction by 100 and put the percent sign,
a a
i.e., = × 100 %.
b b
5. To convert decimals to percentages, we first convert the decimal into fraction, then multiply
by 100 and put % sign or simply multiply the decimal by 100%.

6. To convert percentages to fraction or decimals, we drop the given percent and divide the
number by 100.

7. Profit = S.P. – C.P. (if S.P. > C.P.) Loss = C.P. – S.P. (if C.P. > S.P.)
Profit Loss
Profit percentage = × 100 Loss percentage = × 100
C.P. C.P.
P × R × T
8. Simple Interest (S.I.) is calculated using the formula, S.I. =
100
where, P = principal R = rate of interest T = time in years

Review Exercises

Multiple ChoiCe Questions
1. The ratio of 4 km to 1,800 m is:
(a) 4 : 18 (b) 9 : 20 (c) 20 : 9 (d) 4 : 27
2. The decimal 0.0625 converted to percentage is:

(a) 6% (b) 6.2% (c) 6.25% (d) 62.5%
3. Four numbers in proportion are:

(a) 2, 3, 5, 6 (b) 1, 3, 2, 5 (c) 1, 3, 4, 12 (d) 2, 2, 4, 6
2
4. The fraction expressed as percent is:
3 2
(a) 20% (b) 30% (c) 60% (d) 66 %
3
5. If 20% of a quantity is 3 kg apples, then 80% of it is:
(a) 12 kg (b) 11 kg (c) 15 kg (d) 20 kg

6. Raunak bought a flower vase for ` 120 and sold it for ` 100. He incurred a loss of:
2
(a) 10% (b) 20% (c) 16% (d) 16 %
3

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