Skip over navigation
Cambridge University Faculty of Mathematics NRich logo
menu search
  • Teachers expand_more
    • Early years
    • Primary
    • Secondary
    • Post-16
    • Events
    • Professional development
  • Students expand_more
    • Primary
    • Secondary
    • Post-16
  • Parents expand_more
    • Early Years
    • Primary
    • Secondary
    • Post-16
  • Problem-Solving Schools
  • About NRICH expand_more
    • About us
    • Impact stories
    • Support us
    • Our funders
    • Contact us
  • search

Or search by topic

Number and algebra

  • The Number System and Place Value
  • Calculations and Numerical Methods
  • Fractions, Decimals, Percentages, Ratio and Proportion
  • Properties of Numbers
  • Patterns, Sequences and Structure
  • Algebraic expressions, equations and formulae
  • Coordinates, Functions and Graphs

Geometry and measure

  • Angles, Polygons, and Geometrical Proof
  • 3D Geometry, Shape and Space
  • Measuring and calculating with units
  • Transformations and constructions
  • Pythagoras and Trigonometry
  • Vectors and Matrices

Probability and statistics

  • Handling, Processing and Representing Data
  • Probability

Working mathematically

  • Thinking mathematically
  • Developing positive attitudes
  • Cross-curricular contexts

Advanced mathematics

  • Decision Mathematics and Combinatorics
  • Advanced Probability and Statistics
  • Mechanics
  • Calculus

For younger learners

  • Early Years Foundation Stage

Mixing Lemonade Poster

Age 11 to 14
Challenge Level Yellow star
  • Problem
  • Student Solutions
 
Answer: the first glass tasted stronger
 
How do you know?
 
Method 1: making the same amount of lemon juice
First glass lemon:water 60:200
 
Second glass lemon:water 100:350
 
60$\times$5 = 100$\times$3 = 300
 
200$\times$5 = 1000, so first glass lemon:water 300:1000
 
350$\times$3 = 1050, so second glass lemon:water 300:1050
 
First glass has less water for the same amount of lemon juice so the first glass tastes stronger.
 
 
Method 2: making the same amount of water
First glass lemon:water 60:200
 
Second glass lemon:water 100:350
 
200$\times$7 = 350$\times$4 = 1400
 
60$\times$7 = 420, so first glass lemon:water 420:1400
 
100$\times$4 = 400, so second glass lemon:water 400:1400
 
First glass has more lemon juice for the same amount of water so the first glass tastes stronger.
 
 
 
Method 3: scaling lemon juice to water
 
First glass: scale factor from lemon juice to water is 3.333
 
Second glass: scale factor from lemon juice to water is 3.5
 
There is more water compared to lemon juice in the second glass, so the first glass tastes stronger.
 
 
 
 
 
Method 4: fractions
First glass: $\frac{60}{260} =\frac6{26} = \frac3{13}$ lemon juice
 
Second glass: $\frac{100}{450} = \frac{10}{45} = \frac29$ lemon juice
 
Common denominator: $13\times9$
 
First glass: $\frac3{13} = \frac{27}{13\times9}$
 
Second glass: $\frac27 = \frac{26}{13\times9}$
 
The first glass has a greater fraction of lemon juice so it tastes stronger.

Related Collections

  • Secondary Posters
  • More Posters

You may also like

Arithmagons Poster

Arithmagons Poster

Squares in Rectangles Poster

Squares In Rectangles Poster

Isosceles Triangles Poster

Isosceles Triangles Poster - February 2005

  • Tech help
  • Accessibility Statement
  • Sign up to our newsletter
  • Twitter X logo

The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

University of Cambridge logo NRICH logo