A store has a sale on books. The price is $17.55 for one book, $16.70 each for 2 books, $15.85 each for 3 books, and $15 each for 4 books. If this pattern continues, how much per book will it cost to buy 7 books?

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A store has a sale on books. The price is $17.55 for one book, $16.70 each for 2 books, $15.85 each for 3 books, and $15 each for 4 books. If this pattern continues, how much per book will it cost to buy 7 books?

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Answer 1 · 2016-11-09T11:29:39

$T_{7} = $ 12.45$ $T_7 = $12.45$

Cost for 7 books will be $$ 12.45$ $$12.45$ per book

Explanation:

The price per book forms an AP

$T_{n} : 17.55 16.70 15.85 15$ $T_n: 17.55" " 16.70" "15.85" "15" "$ they all differ by $- 0.85$ $-0.85$

$n : 1234$ $n:" "1" "2" "3" "4$

The cost if 7 books are bought will be $T_{7}$ $T_7$

$T_{7} = a + d (n - 1)$ $T_7 = a + d(n-1)$

$T_{7} = 17.55 - 0.85 \times 6$ $T_7 = 17.55-0.85xx6$

$T_{7} = $ 12.45$ $T_7 = $12.45$

Answer 2 · 2016-11-09T11:34:20

$$ 12.45$ $color(green)($12.45)$

Explanation:

Price difference with each additional book purchased is $$ 0.85$ $$0.85$
$XXX (= $ 17.55 - $ 16.70 = $ 16.70 - $ 15.85 = $ 1585 - $ 15.00)$ $color(white)("XXX")(=$17.55-$16.70=$16.70-$15.85=$1585-$15.00)$

The formula for price per books seems to be:
$XXX p (n) = $ 17.55 - (n - 1) \cdot $ 0.85$ $color(white)("XXX")p(n)=$17.55-(n-1) * $0.85$
where $n$ $n$ is the number of books purchased.

$p (7) = $ 17.55 - 6 \cdot $ 0.85 = $ 17.55 - $ 5.10 = $ 12.45$ $p(7)=$17.55-6 * $0.85 = $17.55 - $5.10 = $12.45$

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A store has a sale on books. The price is $17.55 for one book, $16.70 each for 2 books, $15.85 each for 3 books, and $15 each for 4 books. If this pattern continues, how much per book will it cost to buy 7 books?

2 Answers

Explanation:

Explanation:

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