香港小六数学练习卷（下学期・第二份）百分数、圆周与圆面积、速率与平均数｜16 题、50 分钟

练习卷 · 小学数学

香港小六数学下学期第二份练习卷：小数除法、分数除分数、百分数取部分与反求原数、圆周与圆面积、速率、平均数，共 16 题、50 分钟、满分 100 分；试题全英文，每题附答案与评分要点，题目版及答案版 PDF 可即时打印操卷。

卷面资料　年级：小六　｜　科目：数学　｜　时限：50 分钟　｜　总分：100 分　｜　题数：16

甲部　短答题（8 题，每题 3 分）

计算下列各题（π 取 22/7）。

#	题目	答案与评分要点
1	Work out 4,608 ÷ 12.	4,608 ÷ 12 = 384
2	Work out 3/4 ÷ 9/8. Give the answer in its simplest form.	3/4 ÷ 9/8 = 3/4 × 8/9 = 24/36 = 2/3 (invert the divisor, then cancel).
3	Find 35% of 240.	35% of 240 = 35/100 × 240 = 84
4	25% of a number is 45. Find the number.	The number is 45 ÷ 25% = 45 ÷ 0.25 = 180. (Check: 180 × 25% = 45.)
5	A circle has a radius of 14 cm. Find its circumference. (Take π = 22/7.)	2 × 22/7 × 14 = 88 cm
6	A circle has a radius of 7 cm. Find its area. (Take π = 22/7.)	22/7 × 7 × 7 = 154 cm²
7	A bus travels 240 km in 3 hours. Find its average speed in km/h.	Average speed = distance ÷ time = 240 ÷ 3 = 80 km/h
8	A cuboid measures 15 cm by 8 cm by 6 cm. Find its volume.	15 × 8 × 6 = 720 cm³

列出算式，并写出答案及单位。

#	题目	答案与评分要点
9	There are 640 students in a school. 45% of them are boys. (a) How many boys are there? (b) How many girls are there?	(a) 640 × 45/100 = 288 boys. (b) 640 − 288 = 352 girls. (1 mark for the percentage calculation, 1 for the subtraction.)
10	A train travels 315 km in 3.5 hours. (a) Find its average speed. (b) At the same speed, how long does it take to travel 630 km?	(a) 315 ÷ 3.5 = 90 km/h. (b) 630 ÷ 90 = 7 hours.
11	A round table top has a diameter of 1.4 m. (Take π = 22/7.) (a) Find its circumference. (b) Find its area. (c) A cloth of 2 m² is bought to cover the top. Is the cloth large enough? Explain briefly.	(a) 22/7 × 1.4 = 4.4 m. (b) Radius = 0.7 m; 22/7 × 0.7 × 0.7 = 1.54 m². (c) Yes: 1.54 m² < 2 m², so 0.46 m² of cloth is left over.
12	In a box of 350 beads, 2/5 of them are red. How many red beads are there?	2/5 × 350 = 350 ÷ 5 × 2 = 140 red beads. (1 mark for ÷ 5, 1 mark for × 2.)
13	The marks of five Mathematics tests are 78, 85, 90, 68, 84 (out of 100). (a) Find the total mark. (b) Find the mean mark.	(a) 78 + 85 + 90 + 68 + 84 = 405 marks. (b) 405 ÷ 5 = 81 marks.

图一：书店星期一至五每日售出的图书数量（本，示例数据）

根据图表及题意作答，须列出算式。

#	题目	答案与评分要点
14	The bar chart shows the number of books a shop sold from Monday to Friday. (a) How many books were sold altogether? (b) Find the mean number of books sold per day. (c) What percentage of the total was sold on Thursday? (Give the answer as a percentage.)	(a) 40 + 55 + 35 + 60 + 50 = 240 books. (b) 240 ÷ 5 = 48 books per day. (c) 60 ÷ 240 × 100% = 25%.
15	After Ben spends 35% of his money, he has $520 left. (a) What percentage of his money is left? (b) How much money did he have at first? (c) How much did he spend?	(a) 100% − 35% = 65%. (b) $520 ÷ 65% = $520 ÷ 0.65 = $800. (c) $800 − $520 = $280 spent.
16	A car travels at 72 km/h for 2 hours 15 minutes and then travels 198 km at 66 km/h. (a) Find the distance travelled in the first part of the journey. (b) Find the time taken for the second part. (c) Find the total distance travelled.	(a) 2 hours 15 minutes = 2.25 h; 72 × 2.25 = 162 km. (b) 198 ÷ 66 = 3 hours. (c) 162 + 198 = 360 km. (1 mark for the time conversion.)

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