Answer:
6.5
Step-by-step explanation:
39/6 comes out to 6.5
Wilda can do the job in 4 hours ... she does 1/4 (or 0.25) of it each hour.
Karla can do it in 5 hours ... she does 1/5 (or 0.2) of it each hour.
Wilda worked alone for 1 hour ... 0.25 of the job was done before her helper
arrived. So only 0.75 of the job remained to be done together.
Working together, they accomplish (0.25 + 0.2) = 0.45 of the job in 1 hour.
How many times do they need to do 0.45 of the job in order to finish
the 0.75 of it that remains ? That's the number of hours it will take them,
working together.
0.75 / 0.45 = <em>1 and 2/3</em>
After Wilda worked alone for 1 hour and Karla came along to join her, it will
take them another <em>1 hour and 40 minutes</em> to finish the job and go for a swim.
Answer:
Option C.
Step-by-step explanation:
Answer:
Explanation:
We must write this equation in the form
(
x
−
a
)
2
+
(
y
−
b
)
2
=
r
2
Where
(
a
,
b
)
are the co ordinates of the center of the circle and the radius is
r
.
So the equation is
x
2
+
y
2
−
10
x
+
6
y
+
18
=
0
Complete the squares so add 25 on both sides of the equation
x
2
+
y
2
−
10
x
+
25
+
6
y
+
18
=
0
+
25
=
(
x
−
5
)
2
+
y
2
+
6
y
+
18
=
0
+
25
Now add 9 on both sides
(
x
−
5
)
2
+
y
2
+
6
y
+
18
+
9
=
0
+
25
+
9
=
(
x
−
5
)
2
+
(
y
+
3
)
2
+
18
=
0
+
25
+
9
This becomes
(
x
−
5
)
2
+
(
y
+
3
)
2
=
16
So we can see that the centre is
(
5
,
−
3
)
and the radius is
√
16
or 4
