1 foot = 12 inches
Height of Jacob = 5 feet 6 inches = 5 *12 + 6 = 66 inches
Jacob's <span>shadow = 3 feet = 36 inches
</span>giraffe's shadow = <span>5 feet 9 inches = 5 * 12 + 9 = 69 inches
</span><span>by
the ratio and proportion
∴ </span>Height of Jacob/Jacob's shadow = Height of giraffe/giraffe's shadow
∴ 66/36 = Height of giraffe/69
∴ Height of giraffe = 69 * 66/36 = 126.5 inches = 10 feet 6.5 inches
d = 3 , a₁₂ = 40 and S
= 7775
In an arithmetic sequence the nth term and sum to n terms are
<h3>• a

= a₁ + (n-1)d</h3><h3>• S

=

[2a + (n-1)d]</h3><h3>
where d is the common difference</h3><h3>a₆ = a₁ + 5d = 22 ⇒ 7 + 5d = 22 ⇒ 5d = 15 ⇔ d = 3</h3><h3>a₁₂ = 7 + 11d = 7 +( 11× 3) = 7 + 33 = 40</h3><h3>S₁₀₀ =

[(2×7) +(99×3)</h3><h3> = 25(14 + 297) = 25(311)= 7775</h3>