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WAEC Mathematics 2018 Paper
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© africaexams.com
Question : 18
Total: 50
The mean of 1, 3, 5, 7 and x is 4. Find the value of x
2
4
6
8
Validate
Solution:
Concept:
The mean is the sum of all values divided by the number of values.
Explanation:
Given values:
1
,
3
,
5
,
7
,
x
1, 3, 5, 7, x
1
,
3
,
5
,
7
,
x
.
Number of values,
n
=
5
n = 5
n
=
5
.
Mean
=
4
= 4
=
4
.
So,
1
+
3
+
5
+
7
+
x
5
=
4
\frac{1+3+5+7+x}{5} = 4
5
1
+
3
+
5
+
7
+
x
=
4
.
16
+
x
5
=
4
\frac{16+x}{5} = 4
5
16
+
x
=
4
.
Multiply both sides by
5
5
5
:
16
+
x
=
20
16 + x = 20
16
+
x
=
20
.
x
=
20
−
16
=
4
x = 20 - 16 = 4
x
=
20
−
16
=
4
.
Answer:
x
=
4
x = 4
x
=
4
, which is option B.
© africaexams.com
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