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Unformatted text preview: arithmetic calculating fractions part 3 This is the third part of a 3 part UNIT.
Objeetives to Part 3
When you have worked through part 3, you should be able to
I multiply proper fractions
I divide proper fraetions
' multiply/ divide miaed numbers Multiplication Of. To multiplj,r two fractions Fractions (i) multiply the numbers in the numerators, and m ultipl},r the numbers in the denominators {ii} simplin the fraetion, if possible. F l 2X3 zxa—ﬁ forste l in i — — = — — ~ 
I“ P i 3 5 3 s 5 15 p
ti . _ 2 . . . .
Then step (ii) — can be wrltten more simply as — , noticing that 3 divides 15 S into numerator and denominator.
lt ean make the raleulation easier if the order of the operations in [i] and (ii) are reversed. l
2 3 Z .3" F r
E 3‘1; =3 9‘1 g dividing by 3 onee m the numerator, and onee m
l h 1 the denominator.
_ '2, is: l multiplying numbers in the numerator and
_ l :2: 5 denominator respectively
2
_ '5 The procedure can be demonstrated graphicaller if the multiplication symbol
” a: ” is replaced by the word ” of ”. Start. with 5 “taking uf this
s  ".l arneinit, we have line prneess elf dividing nurneratnr and dennniinatnr by a eninrnnn fat‘ttir is eften referred te as “raneelling”. Examples
1‘ if; f E: tiiyiding nLin'ieratiir and deneminater by 5
25 5
ﬂ = 3_ dividing numeratnr and dentirninatnr by 8
5t: T
2 Mixed nurnbers must be ehanged te in'iprnper [raetiens first. 1 l5 .1 ﬂ : _5_ diyieling numeratnr and tieneininatnr by ti
£4 24 3
Division 13"" In the last seetinn we ealenlated
Fractions .2 3 ﬂ __ K _ : _ .. '3 5 15 This staternent eeuld be reversed tn giye
6 '2 3
15 3 5 "1
Censider what happens if! instead nf tiiyiding by % , we multiply by the 3 1
’i s
Netiee that 1% Ex: :. gx’ggr: {R} Nets: same answer as in (A).
1 Is this just a strange eerineidenee’iI Take a simpler example where a diagram ean help naur thinking. 2 + i HDW mme quarters are there in 2 thIE units?
4
a? QB Answer ti
4
Netiee 2‘2<——2><i =8=3
1 I I l
3 1 New eensider — ' — 4'8 How many eigliths are there in three—quarters? Fm eighth leeks like Hittite alsn that if yeu’re still urieem‘irieecl, trjI,r some mere examples for yeurseli. Keep them
simple enough te draw diagrams. Be there are 6 eighlhs in three—quarters Rule: Te divided by a fraetieri, multiply b}.r its reeiprneal. Examples I
l LEAK—£12
' 3438' 3—6
2 2
7 3 7 .8’ 14 S
12 8 H 3 9 9
3 1 5
.3. _1_1_’:;2_6_J_a' at; _1
5 25‘125‘5'*5‘.ssxsa_2_22
1 2 Cheek all the steps in this ealeulatien fnr ymlreelf. SUMMARY of steps; ' Change mixed numhem intn imprnper fractiene 1' Change division by a fractien into mlllﬁplieatinn by its reeiprneal  Divide numeraters and denerninaters by remmnn farturs (cancelling)
I Multiply numbers in numerator  Multiply numbers in denominator  Ch ange answer to a mixed number, if apprepriate EXB I'ClSE Calculate 1 ixixi
' 1 15 15
1 2
2. :11 11111111152014? “K” far Irﬂfn] 1_ 2
4. 1§T25
1 1_ 3
5 Solutions '1. l 2. _1_.{_l._.3l 3. :11
8 5 5 ‘2
4 5 5 11 ...
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This note was uploaded on 03/16/2011 for the course ECON 1003 taught by Professor Dr.mcdonald during the Spring '11 term at University of the West Indies at Mona.
 Spring '11
 DR.MCDONALD

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