Question

Sammy wants to calculate the time it takes for a ladybug traveling at a speed of 3 inches (in.) per second (sec.) to crawl a distance of 10 feet (ft.).

Starting with the formula d=rt
𝑑
=
𝑟
𝑡
, Sammy rearranges the formula to highlight time, t, as the quantity of interest.

t=dr
𝑡
=
𝑑
𝑟

Sammy substitutes the values for rate and time into the formula t=dr
𝑡
=
𝑑
𝑟
and simplifies to calculate the time.

t=10 ft.3in.sec.t≈3.3 sec.
𝑡
=
10

f
t
.
3
i
n
.
sec
.
𝑡
≈
3.3

sec
.

Sammy determines it takes the ladybug about 3.3
3.3
sec. to travel 10 ft.

What mistake did Sammy make?

(1 point)
Responses

Sammy needed to convert 10 ft. to 120 in. by multiplying by 12 in.1 ft.
12 in.
1 ft.
before substituting.
Sammy needed to convert 10 ft. to 120 in. by multiplying by Start Fraction 12 inches over 1 foot End Fraction before substituting.

Sammy needed to convert 3 in. per sec. to 36 in. per sec. by multiplying by 12 in.1

Answer 1

The mistake Sammy made is in converting the distance from feet to inches. Since there are 12 inches in a foot, Sammy should have converted the distance of 10 feet to inches before substituting into the formula.

The correct conversion would be:
10 ft × 12 in/ft = 120 in.

Therefore, the correct response is:

**Sammy needed to convert 10 ft. to 120 in. by multiplying by \( \frac{12 \text{ in.}}{1 \text{ ft.}} \) before substituting.**