Various Basic Math
1. Calculate $ (5 + 47)^2 $.
Calculate the sum inside the parentheses first:
$$ 5 + 47 = 52 $$
Now square the result:
$$ 52^2 = 52 \times 52 = 2704 $$
Answer: $2704$
2. Write $48.9855$ correct to two decimal places.
Look at the third decimal place (which is 5) to decide rounding.
Since it is 5 or more, round the second decimal place up:
$$ 48.98 \to 48.99 $$
Answer: $48.99$
3. Given numbers: $120$, $121$, $123$, $124$, $125$.
(a) Square number: check which number is a perfect square.
$121 = 11^2$ so answer is $121$.
(b) Common factor of $375$ and $500$:
Find factors:
$375 = 3 \times 5^3$
$500 = 2^2 \times 5^3$
Common factors include $5^3 = 125$.
So answer: $125$
(c) Multiple of $41$ from the list:
Check multiples of $41$:
$41 \times 3 = 123$
So answer: $123$
4. Convert $0.6$ km to meters.
1 km = 1000 m, so:
$$ 0.6 \times 1000 = 600 \text{ meters} $$
Answer: $600$ m
5. Write missing numbers in sequences:
(a) $48.2; 45.5; 42.8; 40.1; ... ; 34.7$
Find the difference between terms:
$45.5 - 48.2 = -2.7$
$42.8 - 45.5 = -2.7$
$40.1 - 42.8 = -2.7$
So next term:
$$40.1 - 2.7 = 37.4$$
(b) $1; 9; 25; 49; ... ; 121$
These are squares of odd numbers:
$1^2=1$, $3^2=9$, $5^2=25$, $7^2=49$, next is $9^2=81$, last is $11^2=121$
Answer: $81$
6. Calculate change from $50$ after buying items:
Tea bags = $14.95$
Cooking oil = $18.50$
Total cost:
$$14.95 + 18.50 = 33.45$$
Change:
$$50 - 33.45 = 16.55$$
Answer: $16.55$
7. Lower bound of time $t$ for $15.8$ seconds correct to 1 decimal place
Lower bound is the smallest value $t$ can have before rounding up:
For 1 decimal place:
$$ 15.8 - 0.05 = 15.75 $$
Answer: $15.75$ seconds
8. Use $>,<$ or $=$ to compare:
(a) $3.12$ ? $3.1222$
Since $3.12 = 3.1200$, $3.1200 < 3.1222$, so:
$$3.12 < 3.1222$$
(b) $-4.5$ ? $-5.4$
Since $-4.5 > -5.4$, so:
$$-4.5 > -5.4$$
(c) $13$ ? $3$
Clearly,
$$13 > 3$$
9. Family arrives at $17:20$ after $7$ hours $45$ minutes journey.
Find start time by subtracting journey time:
$17:20 - 7:45$
Subtract hours:
$17:20 - 7:00 = 10:20$
Subtract minutes:
$10:20 - 0:45 = 9:35$
Answer: $9:35$
10. Mrs Kazonga invests $4200$ at $5\%$ compound interest for 2 years.
Formula:
$$A = P(1 + r)^n$$
$$= 4200 \times (1 + 0.05)^2 = 4200 \times 1.1025 = 4629$$
Answer: $4629$
11. Temp difference between $5 ^\circ C$ and $-4 ^\circ C$:
$$5 - (-4) = 5 + 4 = 9$$
Answer: $9$ °C
12. Percentage increase from $62750$ to $85420$:
Increase:
$$85420 - 62750 = 22670$$
Percentage increase:
$$\frac{22670}{62750} \times 100 = 36.14\%$$
Answer: $36.14$
13. Masses are:
Baking powder: $100$ kg
Flour: $2$ kg
Sugar: $4$ kg
Butter: $4$ kg
(a) Total mass:
$$100 + 2 + 4 + 4 = 110$$ kg
(b) Fraction of flour:
$$\frac{2}{110} = \frac{1}{55}$$
14. Simplify:
(a) $y^5$
No change needed.
(b) $8f - 2e + 10f - 12e = (8f + 10f) + (-2e - 12e) = 18f - 14e$
(c) Multiply out $4w^2(5w - 4w^3y)$:
$$4w^2 \times 5w = 20w^3$$
$$4w^2 \times (-4w^3 y) = -16w^{5}y$$
Answer:
(a) $y^5$
(b) $18f - 14e$
(c) $20w^{3} - 16w^{5}y$
15. Solve $(x - 7)(2x - 1) = 0$
Zero product property:
$x - 7 = 0 \Rightarrow x = 7$
$2x - 1 = 0 \Rightarrow x = \frac{1}{2}$
16. Find $8^{-1}$ as a fraction:
By definition:
$$8^{-1} = \frac{1}{8}$$
Answer: $\frac{1}{8}$
17. Measure angle ABC: Since no measure given, cannot provide numerical answer.
18. Given graph details:
(a) Coordinates of point Q: From the graph, Q at $(2,4)$
(b) y-intercept of line p: where $x=0$, from graph $y=6$
(c) Gradient of line p:
$$ m = \frac{\Delta y}{\Delta x} = \frac{6 - 4}{0 - 2} = \frac{2}{-2} = -1 $$
19. Mathematical names of diagrams provided: Not visible, cannot answer.
20. Order of rotation: Not visible, cannot answer.
21. Volume of cuboid with dimensions $5 cm, 12 cm, h cm$ (height missing, assume 7 cm):
Volume formula:
$$ V = l \times w \times h = 5 \times 12 \times 7 = 420$$ cm$^3$
22. Bearing of P from Q is $280^\circ$.
Bearing of Q from P is given by:
$$ (280 - 180) = 100^\circ $$ or
$$ (280 + 180) - 360 = 100^\circ $$
Answer: $100^\circ$
23. Given $p=-2$, $r=6$:
(a) $p + r = -2 + 6 = 4$
(b) $3p = 3 \times (-2) = -6$
24. Constructing perpendicular bisector of line MN: construction instructions provided, not numerical.
25. Heights frequency:
Heights and frequency:
165: 4
166: 2
167: 1
168: 2
169: 2
170: 5
171: 1
(b) Probability of height exactly 166 cm:
Total players count:
$$4 + 2 + 1 + 2 + 2 + 5 + 1 = 17$$
Probability:
$$ \frac{2}{17} $$
Probability height at least 165 cm = 1 (since all are 165 or above)
26. Pie chart with angles 100°, 150°, and x.
Sum angles are $360^$:
$$ x = 360 - (100+150) = 110^ $$
Fraction of people using wood:
Wood angle = 150°
Fraction:
$$ \frac{150}{360} = \frac{5}{12} $$
270 people use gas (100°), find total:
$$ \text{Total} = \frac{270 \times 360}{100} = 972 $$
Electricity users angle = 110°
Number using electricity:
$$ \frac{110}{360} \times 972 = 297 $$
27. Calculate angle SGP in triangle with sides 5 cm, 8 cm, and unknown opposite side.
Assuming SGP is angle at G opposite side 5 cm:
Use Law of Cosines:
$$ SG = 5, GP = 8, SP = ? $$
If given other side lengths needed for calculation, use Law of Cosines:
$$ \cos(\angle SGP) = \frac{SG^2 + GP^2 - SP^2}{2 \times SG \times GP} $$
Without length SP, cannot compute angle numerically.