Question

gregory has a rectangular prism with a length of 10 cm, a width of 3 cm, and a height of 8 cm. what is the surface area of gregorys rectangular prism? a 134 cm² b 240 cm² c 268 cm² d 486 cm²

Explanation:

Step1: Recall surface - area formula

The surface - area formula of a rectangular prism is $SA = 2(lw+lh + wh)$, where $l$ is length, $w$ is width, and $h$ is height.

Step2: Substitute values

Given $l = 10$ cm, $w = 3$ cm, and $h = 8$ cm. Substitute into the formula: $SA=2(10\times3 + 10\times8+3\times8)$.

Step3: Calculate inside parentheses

First, calculate each product inside the parentheses: $10\times3 = 30$, $10\times8 = 80$, $3\times8 = 24$. Then $10\times3 + 10\times8+3\times8=30 + 80+24=134$.

Step4: Multiply by 2

$SA = 2\times134=268$ $cm^{2}$.

Answer:

C. $268$ $cm^{2}$