2017 - JAMB Mathematics Past Questions and Answers - page 2
11
Simplify 3 \(^{n − 1}\) × 27 \(\frac{n + 1}{81^n}\)
A
3\(^{2n}\)
B
9
C
3n
D
3 \(^{n + 1}\)
correct option: b
3\(^{n + 1}\) × 27\(\frac{n + 1}{81^n}\)
= 3\(^{n + 1}\) × 3 \(\frac{3^{(n + 1)}}{3^{4n}}\)
= 3\(^{n + 1 + 3n + 3 − 4n}\)
= 3\(^{4n − 4n − 1 + 3}\)
= 32
= 9
Users' Answers & Comments= 3\(^{n + 1}\) × 3 \(\frac{3^{(n + 1)}}{3^{4n}}\)
= 3\(^{n + 1 + 3n + 3 − 4n}\)
= 3\(^{4n − 4n − 1 + 3}\)
= 32
= 9
12
The locus of a point which is equidistant from the line PQ forms a
A
circle centre P
B
pair of parallel lines each opposite to PQ
C
circle centre Q
D
perpendicular line to PQ
correct option: d
The locus of points at a fixed distance from the point P is a circle with the given P at its centre.
The locus of points at a fixed distance from the point Q is a circle with the given point Q at its centre
The locus of points equidistant from two points P and Q i.e line PQ is the perpendicular bisector of the segment determined by the points
Hence, The locus of a point which is equidistant from the line PQ forms a perpendicular line to PQ
Users' Answers & CommentsThe locus of points at a fixed distance from the point Q is a circle with the given point Q at its centre
The locus of points equidistant from two points P and Q i.e line PQ is the perpendicular bisector of the segment determined by the points
Hence, The locus of a point which is equidistant from the line PQ forms a perpendicular line to PQ
13
Given T = {even numbers from 1 to 12}
N = {common factors of 6, 8 and 12} Find T, N
N = {common factors of 6, 8 and 12} Find T, N
A
{2, 3}
B
{2, 3, 4}
C
{3, 4, 6}
D
{2}
correct option: b
Given T = {even numbers from 1 to 12}
= { 2, 4, 6, 8,10, 12}
N = {common factors of 6, 8 and 12}
= {2} Find T n N = {2}
Users' Answers & Comments= { 2, 4, 6, 8,10, 12}
N = {common factors of 6, 8 and 12}
= {2} Find T n N = {2}
14
Given the quadrilateral RSTO inscribed in the circle with O as centre. Find the size angle x and given RST = 60o
A
100o
B
140o
C
120o
D
10o
correct option: c
If RST = 60o
RXT = 2 × RST
(angle at the centre twice angle at the circumference)
RXT = 2 × 60
= 120o
Users' Answers & CommentsRXT = 2 × RST
(angle at the centre twice angle at the circumference)
RXT = 2 × 60
= 120o
15
Find the sum of the range and the mode of the set of numbers 10, 9, 10, 9, 8, 7, 7, 10, 8, 10, 8, 4, 6, 9, 10, 9, 7, 10, 6, 5
A
16
B
14
C
12
D
10
correct option: a
Range = Highest Number - Lowest Number
Mode is the number with highest occurrence
10, 9, 10, 9, 8, 7, 7, 10, 8, 4, 6,, 9, 10, 9, 7, 10, 6, 5
Range = 10 − 4 = 6
Mode = 10
Sum of range and mode = range + mode = 6 + 10
= 16
Users' Answers & CommentsMode is the number with highest occurrence
10, 9, 10, 9, 8, 7, 7, 10, 8, 4, 6,, 9, 10, 9, 7, 10, 6, 5
Range = 10 − 4 = 6
Mode = 10
Sum of range and mode = range + mode = 6 + 10
= 16
16
Find the sum to infinity of the series
\(\frac{1}{4}\), \(\frac{1}{8}\), \(\frac{1}{16}\),..........
\(\frac{1}{4}\), \(\frac{1}{8}\), \(\frac{1}{16}\),..........
A
\(\frac{1}{2}\)
B
\(\frac{3}{5}\)
C
\(\frac{-1}{5}\)
D
\(\frac{73}{12}\)
correct option: a
Sum to infinity
∑ = arn − 1
= \(\frac{a}{1}\) − r
a = \(\frac{1}{4}\)
r = \(\frac{1}{8}\) ÷ \(\frac{1}{4}\)
r = \(\frac{1}{s}\) × \(\frac{4}{1}\)
= \(\frac{1}{2}\)
S = \(\frac{1 \div 4}{1}\) − \(\frac{1}{2}\)
= \(\frac{1}{4}\) ÷ \(\frac{1}{2}\)
= \(\frac{1}{4}\) × \(\frac{2}{1}\)
= \(\frac{1}{2}\)
Users' Answers & Comments∑ = arn − 1
= \(\frac{a}{1}\) − r
a = \(\frac{1}{4}\)
r = \(\frac{1}{8}\) ÷ \(\frac{1}{4}\)
r = \(\frac{1}{s}\) × \(\frac{4}{1}\)
= \(\frac{1}{2}\)
S = \(\frac{1 \div 4}{1}\) − \(\frac{1}{2}\)
= \(\frac{1}{4}\) ÷ \(\frac{1}{2}\)
= \(\frac{1}{4}\) × \(\frac{2}{1}\)
= \(\frac{1}{2}\)
17
The base in which the operation was performed was
A
6
B
2
C
4
D
5
correct option: b
Users' Answers & Comments19
In a regular polygon, each interior angle doubles its corresponding exterior angle. Find the number of sides of the polygon
A
8
B
6
C
4
D
3
correct option: b
2x + x = 180o
3x = 180o
x = 60o (exterior angle of the polygon)
angle = \(\frac{\text{total angle}}{\text{number of sides}}\)
60 = \(\frac{360}{n}\)
n = \(\frac{360}{60}\)
n = 6 sides
Users' Answers & Comments3x = 180o
x = 60o (exterior angle of the polygon)
angle = \(\frac{\text{total angle}}{\text{number of sides}}\)
60 = \(\frac{360}{n}\)
n = \(\frac{360}{60}\)
n = 6 sides
20
A cylindrical tank has a capacity of 3080m3. What is the depth of the tank if the diameter of its base is 14m? Take pi = 22/7.
A
23m
B
25m
C
20m
D
22m
correct option: c
Capacity = Volume = 3080m3
base diameter = 14m
radius = \(\frac{\text{diameter}}{2}\)
= 7m
Volume of Cylidner = Capacity of cylinder
πr2h = 3080
\(\frac{22}{7}\) × 7 × 7 × h = 3080
h = \(\frac{3080}{22 \times 7}\)
h = 20m
Users' Answers & Commentsbase diameter = 14m
radius = \(\frac{\text{diameter}}{2}\)
= 7m
Volume of Cylidner = Capacity of cylinder
πr2h = 3080
\(\frac{22}{7}\) × 7 × 7 × h = 3080
h = \(\frac{3080}{22 \times 7}\)
h = 20m