You can round 976 to 1000 and 522 to 500. So it would be
1000 - 500 = 500. The answer you would get after subtracting 976-522 would be more than 400 if you round it.
The number of ways to arrange the 5 writings in a row is 5! = 5 * 4 * 3 * 2 * 1 = 120 ways.
There is only 1 way to arrange the writings from oldest to newest.
Therefore, the probability is 1/120.
Answer 10
This is the formula of an arithmetic sequence.
a
n
=
a
1
+
d
(
n
−
1
)
a
n
=
a
1
+
d
(
n
-
1
)
Substitute in the values of
a
1
=
1
a
1
=
1
and
d
=
3
d
=
3
.
a
n
=
1
+
(
3
)
(
n
−
1
)
a
n
=
1
+
(
3
)
(
n
-
1
)
Simplify each term.
a
n
=
1
+
3
n
−
3
a
n
=
1
+
3
n
-
3
Subtract
3
3
from
1
1
.
a
n
=
3
n
−
2
Wouldn’t the answer be 8 and 3
