Why it happens: Every scooter picture is worth the same, 3. So the row with the most pictures must also stand for the biggest number. You can answer "which day" just by looking, but you still need the key to say how many.
Q2.
How many total two-wheelers did she record over three days? ________
Answer
72 two-wheelers.
Work out each day. Monday 8 × 3 = 24. Wednesday 4 × 3 = 12. Friday 12 × 3 = 36.
Add the three days.
24 + 12 + 36 = 36 + 36 = 72 two-wheelers
Check it yourself another way: Count all the scooter pictures first. 8 + 4 + 12 = 24 pictures. Each is worth 3. 24 × 3 = 72 ✓ Both roads lead to 72, so the answer is right.
Why it happens: Multiplying each row and then adding gives the same answer as adding all the pictures and then multiplying. The 3 is the same for every picture, so it can be taken out and used once at the end.
Q3.
How many fewer two-wheelers were seen on Wednesday than on Monday? ________
Answer
12 fewer.
Find Monday's number. 8 scooters × 3 = 24.
Find Wednesday's number. 4 scooters × 3 = 12.
Subtract the smaller from the bigger, because "how many fewer" asks for the gap between them.
Check it yourself using pictures: The gap is 12 − 4 = 8 pictures, and 8 × 3 = 24 ✓
Why it happens: Friday's row is three times as long as Wednesday's, so Friday had three times as many two-wheelers — 36 instead of 12. Roads are usually busier on a Friday than in the middle of the week.
Q5.
Choose any other scale and represent the same data using a pictograph in your notebook.
Answer
A scale of 6 works well here — 24, 12 and 36 all divide by 6.
The same three days drawn with a scale of 6. Friday's row is still the longest — the story does not change.
Other scales that work:
Scale
Monday (24)
Wednesday (12)
Friday (36)
Comment
1 scooter = 3
8
4
12
The book's own scale
1 scooter = 4
6
3
9
Works, all whole
1 scooter = 6
4
2
6
Neatest — fewest pictures
1 scooter = 12
2
1
3
Very few pictures, but hard to see the difference
1 scooter = 5
4 4/5
2 2/5
7 1/5
Do not use — the pictures do not come out whole
Why it happens: A good scale must divide every number in the data. 3, 4, 6 and 12 all divide 24, 12 and 36. Five does not, so a scale of 5 would force you to draw awkward part-pictures.
Remember: Changing the scale never changes the data. Friday is the busiest day whichever scale you pick.