The speed of a tsunami in km per hour can be found using s = √4.4944d, where d is
the water depth. Suppose the water depth is 1000 m. How fast is the tsunami moving in
km per hour?
Answers
Answer:
4142.733
Solution:
4142733
× ÷
=
4143732
× ×
=
4747
× =
Example 9:
Using appropriate properties, find
− −
× + + ×
25722.37337
Solution:
2572237337
− −
× + + ×
=
5222773733
−× − × +
12/04/18
=
52277733
−
− × +
=
− + =
275333
c
be the three rational numbers where
= =
24,35
a b
and
56
c
=−
× × = × ×
Example 13:
Solve the following questions and write your observations.(i)53+ 0 = ?(ii)25
−
+ 0 = ?(iii)37 + 0 = ?(iv)
23
× 1 = ?(v)
67
−
× 1 = ?(vi)
98
× 1 = ?
Solution:
(i)
53
+ 0 =
53
(ii)
25
−
+ 0 =
25
−
(iii)
37
+ 0 =
37
Rational NumbersIntegers Whole Numbers
12/04/18
(iv)
23
× 1 =
23
(v)
66177
− −× =
(vi)
98
× 1 =
98
Observation
From (i) to (iii), we observe that: (i) When we add 0 to a rational number weget the same rational number.From (iv) to (vi), we observe that: (ii) When we multiply a rational number by 1 we get the same rational number.(iii) Therefore, 0 is the
additive identity
of rational numbers and 1 is the
‘multiplicative identity’
of rational numbers.
Example 14:
Write any 5 rational numbers between
56
−
and
78
.
Answer:
Canvas required=πrl+2πrh=πr(l+2h)
=
7
22
×
2
105
(53+3×2)
=165×59
=9735㎡
Let length of canvas be l then
l×5=9735㎡⇒l=
5
9735
=1947m
Therefore, length of canvas=1947m