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40 votes
40 votes
An element with a mass of 700 grams decays by 6.1% per minute. To the nearest

tenth of a minute, how long will it be until there are 220 grams of the element
remaining?

User Berkeley
by
2.8k points

2 Answers

24 votes
24 votes

Answer:

18.4

Explanation:

I answered the question

User Jan Chalupa
by
3.0k points
15 votes
15 votes

Answer:

11.2 minutes

Explanation:

If the element decreases by 6.1, every minute, it means that the mass lost every minute = 0.061 x 700g = 42.7g

The mass remaining after a minute = 657.30g

The equation that can be used to solve this question is :

700 - 42.7m = 220

m = minutes

Collect like terms

700 - 220 = 42.7m

480 = 42.7m

divide both sides of the equation by 42.7

m = 11.241218 minutes

the tenth is the first number after the decimal place. To convert to the nearest tenth, look at the number after the tenth (the hundredth). If the number is greater or equal to 5, add 1 to the tenth figure. If this is not the case, add zero

Here, the hundredth is less than 5, so zero would be added to 2. the answer is 11.2 minutes

User Tataelm
by
2.8k points