This preview shows pages 1–4. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: arithmetic calculating fractions part 2
— When you have worked through part 2, you should be able to  select from sets of equivalent fractions those with a common denominator ' addf subtract proper fractions
I addf subtract mixed numbers This is the second part of a 3part UNIT.
Pre—requisite: You should know how to generate sets of equivalent fractions. Addition and . Example Caiculaeiﬁ
Subtraction which have a common denominator, in this case, 6. Then %+% = 2 +% = 2 (adding the numerators) 6 The fractions from each set which had the smallest common denominator were 4 chosen. This is desirable, though not essential. We might have used E and
E1
— . with common denominator 12; i + i = i + E. = 1—9.
12 s 2 12 12 1::
. 10 . . . . 5
and then said 1—,: 15 equivalent to the simpler fraction Choosing the smallest common denominator simplifies the work and saves time. . 2 3
Examples 1. Fmd 3+? (pd siﬁaeee_201
“ml was 15‘10‘15’20’25*3o‘ss‘ 40 “50‘ d {3: 2 i _I2 _15 1
a“ 3’ 16’ 24’ 32’ 40 "'1 and choose fractions with common denominator 40. 23161531 Then ~—+—=++——=— (addingnumerators).
5 3 40 4'1] 40 i
. 3 4
2. Find 5  7.
a . 3 6 9 12 15 18 21 l
L. cl t — _ _ _. _ _... _..
mm m“ 15’ 10’ 15 20’ 25’ 30* as l
and __8... E E E i
T14“ 1' 23' 35 1
Then 2—i2EEzi {subtractingnumerators}.
5 7 ’3‘? 35 The process can he speeded up. It is not essential to generate whole sets of
equivalent fractions each time. Step {i} Look for a common denominator
In this example, that is a number that 5 and '5” will divide into.
Choose 35.
E _ 4 i
5 7 35 35
Step {ii} Find equivalent fractions
3 P’
E h 33 Ask yourself “What has 5 been multiplied 13}; to give 35”.
The answer is .7. Multiply the numerator bv the same number. Then §=ﬂ:3}tl 5 a7 35 Repeat the argurnent fer i i = £32 = 2—2.
3 7 7’ 7 3x:
Step {iii} Add er subtract as required. Further 3. Calculate 3+§_i
Examples 5 4 2
. 2 3 l 5'" ? ?
3919(1) 34—1—5 = Tiatiﬁﬁ eernrnen denerninater 20 Step(e) 3:2X4=_8_. 5 5x4 EU 3 _ 3x5 _ 4 ‘ 4x5 ‘ 20 l>< If} 10 3 l 8 15 it} 13
_+__._..._.._._._— E E 20 20 zit—E E
ﬁll
"e
e; Lnllﬂ + I II While we eften en 13.? write the calculatien as in step (iii), the theught
preeesses in {i} and {ii} are essential. 4. Mixed. Numbers 2:113: 6 4 3 and a bit! by adding the whele numbers. 5 3 10 9 19
se 6 4 12 12 12 adding the fraeeens. New % is greater than 1 and can be written as %+% Let l+132 er 1%. Adding the three whele numbers, the tetal stun is 41%.
5 q:_132§_: '4883 Here we need te change ene ef the whele numbers inte eighths. 7 35' __
8 8 m _8 67
—[+8+8 3 HF'
equal te
E = 1 adding /subtrarting numeraters ee~a Sum mary 1. Addfsubtraet whale numbers
Find smallest eemen denemﬂ'lster fer the fractions.
Find equivalent fractiens. Add! subtract numereters of fractions, if possible. P1P?!” If Step 4 cannot be done, change 1 whole number into a fraetien.
Then do Step 4. 6. Can the ﬁnal fraeﬁen be simpliﬁed? Exercise Calculate the fellewing: 1 %+%+% 2. es s 3%; 4 2%+%—1% s 3%—1%+2%
Solutions 1. %=I% 2+ % 3 2130. 4 1% ...
View
Full
Document
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

Click to edit the document details