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Anonymous
Anonymous asked in Science & MathematicsMathematics · 2 months ago

GCSE Foundation Maths question...?

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  • 2 months ago

    Car A completes 5 laps in 150 seconds. 

     

    The number of seconds car B takes to complete a lap must be a whole number 

    and a factor of 150 (so it completes a lap at 150 seconds after the start), 

    BUT it cannot be a factor of 30. 

    If it were, car B would complete a lap every time car A does. 

     

    Looking at the factorizations of 30 and 150, we can see that the only way 

    a factor of 150 cannot divide 30 is if it is a multiple of 25 

    so both the 5s in the factorization of 150 come into play. 

     

    So we are looking at possible factors of 

    2 * 3 * 5 * 5 

    that include the 5 * 5 part. These are 

    5 * 5 = 25 (Car B completes its sixth lap 150 seconds after the start.) 

    2 * 5 * 5 = 50 (Car B completes its third lap then.) 

    3 * 5 * 5 = 75 (Car B completes its second lap then.)  

    2 * 3 * 5 * 5 = 150 (Car B completes its first lap then.) 

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