Tables And Rates
1. Problem: Complete the tables and plot the points for each given rule.
2. For (a) $y = x + 2$, substitute each $x$:
- $x=0 \Rightarrow y=0+2=2$
- $x=1 \Rightarrow y=1+2=3$
- $x=2 \Rightarrow y=2+2=4$
- $x=3 \Rightarrow y=3+2=5$
- $x=4 \Rightarrow y=4+2=6$
- $x=5 \Rightarrow y=5+2=7$
Completed table:
$x$: 0 1 2 3 4 5
$y$: 2 3 4 5 6 7
3. For (b) $q = p - 1$, compute $q$:
- $p=1 \Rightarrow q=0$
- $p=2 \Rightarrow q=1$
- $p=4 \Rightarrow q=3$
- $p=5 \Rightarrow q=4$
- $p=6 \Rightarrow q=5$
- $p=7 \Rightarrow q=6$
Completed table:
$p$: 1 2 4 5 6 7
$q$: 0 1 3 4 5 6
4. For (c) $n = m - 1$, compute $n$:
- $m=1 \Rightarrow n=0$
- $m=2 \Rightarrow n=1$
- $m=3 \Rightarrow n=2$
- $m=4 \Rightarrow n=3$
- $m=6 \Rightarrow n=5$
- $m=8 \Rightarrow n=7$
Completed table:
$m$: 1 2 3 4 6 8
$n$: 0 1 2 3 5 7
5. For (d) $c = \frac{d}{2} - 1$, compute $c$:
- $d=0 \Rightarrow c=0/2-1=-1$
- $d=2 \Rightarrow c=2/2-1=1-1=0$
- $d=4 \Rightarrow c=4/2-1=2-1=1$
- $d=6 \Rightarrow c=6/2-1=3-1=2$
- $d=7 \Rightarrow c=7/2-1=3.5-1=2.5$
- $d=8 \Rightarrow c=8/2-1=4-1=3$
Completed table:
$d$: 0 2 4 6 7 8
$c$: -1 0 1 2 2.5 3
6. Exercise 4:
Number of hours (t): 2, 3, 4, 5, 7, 10
Kilometres covered (k): 160, 240, 320, 500, 950, 1200
7. (a) Find constant speed $v$ using $v = \frac{\Delta k}{\Delta t}$ between points with constant rate.
Check from 2 to 3 hours:
$$v = \frac{240 - 160}{3 - 2} = \frac{80}{1} = 80$$ km/h
From 3 to 4 hours:
$$v = \frac{320 - 240}{4 - 3} = 80$$ km/h consistent
From 4 to 5 hours:
$$v = \frac{500 - 320}{5 - 4} = 180$$ km/h not consistent
Since speeds vary, speed is NOT constant but roughly $80$ km/h early and then increases.
8. (c) i) After 5 hours, kilometres: 500 (given)
ii) After 18 hours, assuming early speed 80 km/h extrapolated approx:
$$k = 80 \times 18 = 1440$$ km
iii) Time $t$ to cover 640 km assuming constant speed 80 km/h:
$$t = \frac{640}{80} = 8 \text{ hours}$$
iv) Time for 280 km:
$$t = \frac{280}{80} = 3.5 \text{ hours}$$
9. (d) If Moshe drives all day (say 24 hours - 1 hour break = 23 hours):
$$k = 80 \times 23 = 1840$$ km
10. Exercise 4.2:
Milk (L): 3, 5, 6, 7, 8, 9
Prices: 12, 20, ?, ?, ?, ?
Find price per litre:
Between 3 L and 5 L:
$$\text{price per litre} = \frac{20 - 12}{5-3} = \frac{8}{2} = 4$$ per litre
Complete prices:
- 6 L: $4 \times 6 = 24$
- 7 L: $4 \times 7 = 28$
- 8 L: $4 \times 8 = 32$
- 9 L: $4 \times 9 = 36$
11. (c) Find litres with R50:
$$\text{litres} = \frac{50}{4} = 12.5 \approx 13 \text{ litres}$$
12. (d) Cost of 10 litres:
$$10 \times 4 = 40$$
13. (e) Cost of 30 litres:
$$30 \times 4 = 120$$
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Final answers: see above tables and calculations.