224 Topics in arithmetic (Chapter 10)5 Which investment would earn you more interest on an 8000 peso investment for 5 years:
one which pays8%p.a. simple interest or one which pays 7 :5%p.a. compound interest?
6 How much do I need to invest now at a fixed rate of interest if I need it to amount to:
a $2000in 4 years at 7 :2%p.a. compounded
b $20 000in 312 years at 6 :8%p.a. compounded?7 Calculate the rate at which compound interest is paid if:
abE 5000 becomesE12 424after 17 years.
8 Molly invests$6000at5%p.a. fixedsimpleinterest. Max invests$6000at 4 :5%p.a. fixedcompound
interest.
a Which is the better investment for 4 years and by how much?
b Which investment is better after 30 years and by how much?9 The value of a car halves in 3 years. Find its annual rate ofdepreciationor loss in value.
10 After 4 years a tractor purchased forE58 500has a resale value ofE35 080. Find its annual rate of
depreciation.We are all familiar with the concept of speed, or how fast something is moving.The following triangle may help you with these rearrangements:
Cover the variable you are trying to find to see how it can be
expressed in terms of the other two variables.Example 22 Self Tutor
Clark runs a 42 : 2 km marathon in 3 hours 5 mins and 17 s.
Find his average speed in km/h.3 hours 5 min 17 s=3+ 605 + 360017 hours
=3:088 055::::::hoursClark’s average speed is about 13 : 7 km/h.G SPEED, DISTANCE AND TIME [1.13]
d
st
$1000becomes$1973: 82 after 6 yearsTheaverage speedsis calculated by dividing the total distance travelleddby
the total time takent. It is the distance travelledper unit of time. s=d
tFor example, if I cycle 60 km in 3 hours then d=60km and t=3hours, and my average speeds=60 km
3 h=20km/h.Notice that s=d
tcan be rearranged to t=d
sand d=st.) s=d
t=
42 : 2 km
3 :088 055::::::h
¼ 13 : 7 km/hIGCSE01
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Y:\HAESE\IGCSE01\IG01_10\224IGCSE01_10.CDR Friday, 14 November 2008 12:11:48 PM PETER