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Practice
Questions
Clement Radcliffe,
Contributor
 |
| Ashley
Douilliard of St. Andrew High School for Girls entertains during the World YWCA
Day 'Round the World breakfast', at 16 Beverly Drive, St. Andrew, on April 24,
under the theme 'Honouring Women Leaders'. - Andrew Smith/ Photography Editor |
As we continue
our review of Directed Numbers, I will share with you the answers to the problems
given for homework last week.Evaluate
the following: (i)
-5 x -3 = 15
(ii)
-21  3 = -7 
(iv)
-8 -10 + 6 = -12 (v)
5a x -6b = -30ab (vi)
12/25 + 5/9 5/18
12/25
x 5/9 5/18 = 12/25
x 5/9 x 18/5 = 24/25 If
the above posed no difficulty, then you are ready to consider exam type questions. Application
of the Foour Arithmetic Operations to Vulgar Fractions In
applying the four basic operations to vulgar fractions, students are required
to observe the correct law with respect to the order of operation as follows: B
- Brackets
O
- Of (Multiply)
M - Multiply
D - Divide
A -
Add
S - Subtract
BOMDAS identifies the order in which
the operations should be carried out and must always be obeyed. Let's
practice the use of BOMDAS (a)
Practice 1 Calculate
the value of: 1 1/2 + 5 x 2
1 2/3 Convert
to Common Factor
= 3/2 + 5 x 2
5/3 We
do the multiplication first: 3/2
+ 10 5/3 We
then do the division:
3/2 + [10 x 3/5]
=
3/2 + 6
= 7 1/2 (b)
Practice 2 | 4
x (2 1/3 + 1/2) | We
first do the brackets (although we are required to add): | | ie.
(2 1/3 + 1/2) = 7/3 + 1/2 | Using
the L.C.M. of 2 and 3, that is 6, we get | = | (2
x 7) + (3 x 1) | | 6 | | = | 14
+ 3 | = | 17 | | 6 | | 6 |
To
complete the problem, we now multiply:
4 x 17/6 = 68/6 = 11 2/3
(c)
Practice 3 | Calculate
the value of: | 6
1/3 - 1 5/6 | | | 1
1/2 x 2 2/3 |
The
line represents brackets and so the numerator may be evaluated first. | 6
1/3 - 1 5/6 | =
19/3 - 11/6 | | | =
(2 x 19) - (1 x 11) | | | 6 | | | | =
38 - 11 = |
27 | | | 6 | 6 |
Evaluating
the denominator: 3/2
x 8/3 = 24/6 Dividing:
= 27/6
24/6 = 27/6 x 6/24 = 9/8 Please
to note - In
solving a problem such as Practice 3, you may first evaluate either the
numerator or the denominator.
- Finding
the L.C.M. CORRECTLY is a very important step in the solution.
- As
Practice 3 requires the exact value, you are not allowed to express the
fraction in decimal form. If this is done, then your answer would be difficult
from 9/8 and you may be penalized.
- Your
working must be always clearly shown in logical sequence.
Let
us now work the following together: Using
a calculator, or otherwise, determine the exact value of
(3.7)²
- (6.24 - 1.3). Solution (3.7)²
- (6.24 - 1.3)
Using the recommended approach, we first evaluate the bracket. (3.7)²
= 13.69 and (6.24 - 1.3) = 4.80
= 13.69 - 4.80 = 8.89
Ans = 8.89 I
close this week with the following: 1.
Calculate the value of 4 1/2 x 2/3 - 1/4 2.
Evaluate: 7/10 [2/5
+ 4/15 x 3/5] 3.
Simplify [2 1/3 - 1 5/8]
1 1/3 4.
Find the value of: 18.75 - (2.11)²
(No. 1 (a) (ii), CXC January 2006) | 5.
Find the value of: | 2
1/4 x 4/5 | (No.
1 (a) (i), CXC January 2006) | | | 3/5
- 1/2 |
Finally,
let us urge you to keep all of these lessons together in a scrap book so that
you can always refer to them. If you require previous copies you should be able
to access these from the Gleaner Company. Clement
Radcliffe is the principal of Glenmuir High School in May Pen. | 
