# Mathematics (2015) | Study Mode

Question 11
A

x = 1.75 or - 0.15

B

x = 2.12 or - 0.79

C

x = 1.5 or - 0.34

D

x = 2.35 or -1.23

Question 12
A

nth = 3

B

nth = 4

C

nth = 5

D

nth = 6

##### Explanation

Nth term of a linear sequence (AP) = a+(n - 1)d

first term = 6, last term = 10 sum - 40

i.e. a = 6, l = 10, S = 40

sn = n 2(2a + (n - 1)d or Sn = 2 (a + b)

Sn = n 2(a + l)

40 = n 2(6 + 10)

40 = 8n

8n = 40

8n = 40

N = 40/8

= 5

The nth term = 5

Question 13
A

y = $$\frac{3x}{4}$$

B

y = $$\frac{4x}{3}$$

C

y = $$\frac{2x}{3}$$

D

y = $$\frac{x}{2}$$

Question 14
A
N132.50K
B
N136.30K
C
N125.40K
D
N257.42K
##### Explanation
$$A = P \left(1 + \frac{r}{100}\right)^n$$

Where P = 126, r = 4,n = 2

A=126 $$\left(1 + \frac{4}{100}\right)^2 \text{Using LCM}$$

=126 $$\left(\frac{100+4}{100}\right)^2 = 126 \left(\frac{104}{100}\right)^2$$

=126 $$\left(1.04^2 \right)$$

= 126 * 1.04 * 1.04

=136.28

A = 136.30 (approx.)

The Amount A, = N136.30k

Question 15
A

x = 5[(s -2) t] + 3yt

B

x = 25[(s -2) t] -3ty

C

x = [1 (s -2)3ty]

D

x = [5(s -2) 2 3ty] $$\times$$ t

##### Explanation

2 + t/5(x + 3/5y ) = s

t/5(x + 3/5y ) = s - 2

[(t(5x + 3y) 25)] = s - 2

t(5x + 3y) = 25 (s - 2)

5x + 3y = [(25(s - 2)) t]

5x = [(25(s - 2)) t] - 3y

Divide both sides by 5

x = [25(s - 2) - 3ty)] 5t

Question 16
A
1.761
B
1.354
C
1.861
D
2.549
##### Explanation
log520 = x

5x = 20(Take log10 of both sides)

log5x = log20

xlog5 = log20

x= [log20 log5]

[1.30103 0.69897]

x = 1.861

Question 17
A

3%

B

2%

C

5%

D

4%

##### Explanation

I = A - P

= N588 - N525

-I = N63

I = PRT 100

R = [100I PT]

R = [(100 $$\times$$ 63 ) (525 $$\times$$ 3)]

= (6300 1575) = 4

- The rate = 4 %

Question 18
A

-3 $$\leq$$ t $$\leq$$ 1

B

-2 $$\leq$$ t $$\leq$$ 3

C

-3 $$\leq$$ t $$\leq$$ 4

D

-3 $$\leq$$ t $$\leq$$ 2

##### Explanation

2t - 1 $$\leq$$ 3 and 2 - t < 5

2t $$\leq$$ 3 + 1 and 2 - 5 $$\leq$$ t

2t $$\leq$$ 4 and - 3 $$\leq$$ t

t $$\leq$$ 2 and - 3 $$\leq$$ t or t $$\geq$$ - 3

Combining the two ,starting from the last

-3 $$\leq$$ t $$\leq$$ 2

Question 19
A

{1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15}

B

{1, 2, 3, 5, 6, 8, 12, 15}

C

{2, 4, 5, 9, 12, 15}

D

{1, 5, 6, 7, 8, 9, 12, 15}

##### Explanation

{A $$\cup$$ B $$\cup$$ C}

{A $$\cup$$ B} = {1, 3, 5, 7, 9, 12, 15}

C={2,4,6,8}

{A $$\cup$$ B} $$\cup$$ C = {1, 3, 5, 7, 9, 12, 15} $$\cup$$ {2, 4, 6, 8}

= {1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15}

{A $$\cup$$ B} $$\cup$$ C = {1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15}

Question 20
A

2

B

1

C

$$0$$

D

3