حل السؤال 18، 4MA1/1H يونيو 2023: المدرجات التكرارية (فئات غير متساوية)

1. 1The two missing frequencies add up to 140 − 23 − 18 − 14 = 85
2. 2On the histogram the two drawn bars cover 34 cm squares altogether
3. 3So 1 cm square stands for 85 ÷ 34 = 2.5 people
4. 4The 5 to 15 bar covers 10 cm squares, so its frequency is 10 × 2.5 = 25
5. 5The 15 to 30 bar covers 24 cm squares, so its frequency is 24 × 2.5 = 60
6. 6For the missing bars, frequency density = frequency ÷ width
7. 70 to 5: 23 ÷ 5 = 4.6; 30 to 40: 18 ÷ 10 = 1.8; 40 to 60: 14 ÷ 20 = 0.7

Answer5 < t ≤ 15 is 25 and 15 < t ≤ 30 is 60; bars of frequency density 4.6, 1.8 and 0.7