Apps. and Interpretation for IBDP Maths Ebook 1 | Page 67

Exercise 18
1. The lengths of the sides of a 20-sided polygon form an arithmetic sequence. The two
shortest sides are 1.5 m and 1.9 m respectively.
(a)
(b)
Find the length of the longest side of the polygon.
Find the perimeter of the polygon.
[3]
[3]
2. Consider the following sequence of figures.
Figure 1 Figure 2 Figure 3
Figure 1 contains 12 edges and Figure 2 contains 23 edges.
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(a) Given that Figure n contains 221 edges, find n .
(b) Find the total number of edges of Figure 18, Figure 19 and Figure 20.
[3]
[3]
3. Workers are drilling for oil in a large-scale project in Saudi Arabia. The costs of oil
drilling to a depth of 10 m and a depth of 20 m are $7500 and $9300 respectively. It costs
an extra constant amount for every subsequent extra depth of 10 m.
(a) Find the cost of drilling to a depth of 100 m.
[3]
(b) The budget of the large-scale project is $340000. Find the greatest possible depth
to be drilled.
[4]
4. In the theatre of a town hall, there are 24 rows in total. The number of seats in each row
forms an arithmetic sequence. The number of seats in the second row and the third row
are 30 and 32 respectively.
(a)
(b)
Find the number of seats in the 24th row.
[3]
The price of a ticket in the theatre is $75. Find the total income of the theatre if all
tickets are sold.
[4]
www.seprodstore.com
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