MAT-144 · Mathematical Reasoning Topic 02 · Conversions & Budgeting
Topic 02 · Review · Q5

Converting between compound units

Two-part: convert a compound unit (mph → km/h), then use it to compute a distance over time.

01 Worked Example Video

Every step of Converting between compound units explained on video. Pause anywhere; the embed scrolls independently of the page.

YOUTUBE
02 What This Looks Like on ALEKS

ALEKS randomizes the numbers each attempt, but the question shape stays the same. Here are two example versions you might see.

Convert the speed

A cyclist rides at 10 miles per hour. What is this speed in km/h?

Use 1 mi = 1.6 km. Don’t round.

speed =
Distance in 4 hours

Using the converted speed (16 km/h), how far will the cyclist travel in 4 hours?

distance =
Heads up: Your ALEKS version will use different numbers. The numbers in the practice below are different too — that way you're exercising the move, not memorizing one answer.
03 The Rule
Compound units have a top and a bottom convert each piece that changes
distance = speed × time
For mph → km/h, only the top (miles) changes. The bottom (hours) stays put, so you only need one factor. Then use the converted speed when computing distance, so the answer lands in the target unit. See it live: compound units in Hard mode →
Common slips
(1) Don’t round. ALEKS asks for the exact answer (10 × 1.6 = 16, exactly). Rounding 1.6 to 2 “to make it easier” throws the whole answer off. (2) Used the wrong speed for the distance. For the distance question, use the converted speed (km/h), not the original (mph), or your answer will be in the wrong unit.
04 Practice — Step by Step
Practice this problem step by step
A truck moves at 50 mph. What is its speed in km/h, and how far does it travel in 2 hours? Use 1 mi = 1.6 km.
Step 1

Convert the speed

Convert 50 mph to km/h. Use 1 mi = 1.6 km.
speed =
Step 2

Which speed for the distance?

To compute distance in km, which speed do you use?
Step 3

Compute the distance

Multiply 80 km/h × 2 h.
distance =
Q4 Q6
MAT-144 · TOPIC 02 · REVIEW · Q5 OF 06