","difficulty":3,"difficultyBand":"hard","totalMarks":3,"sourceTitle":null,"calculatorUse":"non_calc","parts":[{"id":"84bda5a1-ba61-4afd-ae73-8759d2fdfc46","label":"a","content":"Calculate an estimate for the mean height of the sunflowers.","markscheme":"- Award method mark for midpoints: 110, 125, 135, 145, 165 M1\n- Award method mark for $\\sum f x = 220 + 625 + 945 + 580 + 330 = 2700$ and dividing by 20 M1\n- Final answer 135 A1","marks":3,"order":0,"markingRubric":{"totalMarks":3,"points":[{"id":"p1","marks":1,"description":"Evidence of using midpoints: 110, 125, 135, 145, 165.","code":"M"},{"id":"p2","marks":1,"description":"Calculation of total estimated height (2700) divided by 20.","code":"M"},{"id":"p3","marks":1,"description":"Correct final answer of 135.","code":"A"}],"finalAnswers":["135"],"generatedAt":"2026-05-06T14:00:46.543Z","modelVersion":"gemini-3-flash-preview"},"explanation":{"methods":[{"id":"midpoint_estimate","label":"Use class midpoints","steps":[{"type":"text","order":0,"title":"Find each midpoint","content":"Because the exact heights are not given, represent each class by its **midpoint**: add the two class boundaries and divide by $2$.\n\n| Height class (cm) | Midpoint, $x$ (cm) |\n|---|---:|\n| $100

Height ( $h\,$ cm)	Frequency
$\leq 120$	2
$\leq 130$	5
$\leq 140$	7
$\leq 150$	4
$\leq 180$	2

Height ( $h\,$ cm)	Frequency
$\leq 120$	2
$\leq 130$	5
$\leq 140$	7
$\leq 150$	4
$\leq 180$	2

Averages from Frequency Tables

Question 21

Averages from Frequency Tables Questions

Averages from Frequency Tables

Question 21

Averages from Frequency Tables Questions