Multiple choice

Anna and Britney start walking from city A to city B at the same time. The distance between the cities A and B is 60 kilometres. Anna travels 4 kmph slower than Britney. When Britney reaches city B, she at once turns back, meeting Anna 12 km away from city B. Which of the following could be the speed of Britney?

  1. 8 kmph

  2. 12 kmph

  3. 16 kmph

  4. 15 kmph
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let Britney's speed be v and Anna's be v-4. Britney travels 60 km and then returns 12 km, total 72 km. Anna travels 60 - 12 = 48 km. Since times are equal, 72/v = 48/(v-4). Solving gives 72v - 288 = 48v, so 24v = 288, v = 12.

AI explanation

When they meet, Britney has traveled 60 plus 12 kilometers, which is 72 km, while Anna has traveled 60 minus 12 kilometers, which is 48 km. Because they walked for the same amount of time, the ratio of their speeds equals the ratio of their distances, which is 72 to 48, or 3 to 2. Let the speeds of Britney and Anna be 3y and 2y respectively. Since Anna travels 4 kmph slower, 3y minus 2y equals 4, making y equal 4, so Britney's speed is 12 kmph.

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