Yes, Applaa is completely free to download and use. There are no subscriptions, no in-app purchases, and no hidden fees. A Pro plan is available for users who want additional AI credits.

What age is Applaa for?

Applaa is designed for kids and young adults aged 7 to 20. The platform scales from beginner drag-and-drop coding to advanced Python, JavaScript, React, and AI/ML.

Is Applaa safe for children?

Yes. Applaa is fully COPPA compliant, shows no advertisements of any kind, uses AI content moderation on all generated content, and provides a parent visibility dashboard so parents can monitor their child's activity.

What can kids build with Applaa?

Kids can build web apps, mobile apps, games, and digital tools using AI assistance. They describe their idea in plain English and Applaa's AI builds working code instantly. Creations can be published to the Applaa Marketplace where kids can earn real money.

What coding languages does Applaa teach?

Applaa's Academy covers Python, JavaScript, React, TypeScript, HTML/CSS, and AI/ML concepts across 130+ free lessons and 150+ challenges.

Does Applaa work on Windows and Mac?

Yes. Applaa is available as a free desktop app for both Windows and macOS. No sign-up is required to get started.

Back to questions directory

A-Level MathematicsYear 2022Q5

14   5. The concentration of an air pollutant is measured in micrograms/m3 Samples of air were taken at two different sites and the concentration of this particular air pollutant was recorded. For Site A the summary statistics are shown below. number of samples s 2 A Site A 13 6.39 For Site B there were 9 samples of air taken. A test of the hypothesis H0 : σ 2 A = σ 2 B against the hypothesis H1 : σ 2 A ≠ σ 2 B is carried out using a 2% level of significance. (a) State a necessary assumption required to carry out the test. (1) Given that the assumption in part (a) holds, (b) find the set of values of s 2 B that would lead to the null hypothesis being rejected, (4) (c) find a 99% confidence interval for the variance of the concentration of the air pollutant at Site A. (3) ___________________________________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Turn over 15   Question 5 continued _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________________________________________ (Total for Question 5 is 8 marks)

Paper Source:9fm0-4b-que-20220628.pdf

Get full Socratic AI guidance on this question — free in the Applaa desktop app

Appy Buddy guides you step-by-step toward the answer without giving it away. Type your attempt and get instant, mark-scheme-aware clues that teach you to think like an examiner.

Download Applaa Free →

Applaa Desktop App

Join Applaa Community

Create your own games, learn AI concepts, program interactive apps, and share with a kid-safe community approved by parents. Free forever on Windows and Mac.

Download Free

Available for Windows and macOS · COPPA Compliant

Exam Specification Info

This question is part of the UK A-Level Mathematics syllabus. In the actual exam, structured questions typically require linking specific keywords to gain full marks. Applaa helps you drill these topics.

Syllabus levelAdvanced Level (A-Level)

SubjectMathematics

Official MarksVariable (2–6 marks)