Divide 30 by half and add ten. What do you get?

2009-12-28 3:12 pm
ok here is another question i looked at and someone said the asnwer is
30x2=60 plus 10 that would be 70. ? is this correct?

my guess was that its 25

30 devided by half (50%) = 15 + 10 = 25

回答 (9)

2009-12-28 3:16 pm
✔ 最佳答案
30/2+10= 15+10 =25

the confusion lies in the wording, and I agree its not especialy clear.
It should say

divide 30 in half,
30 / 2 +10 =25

divide 30 by one half
30/(1/2) +10 =70

Give both answers, I have found the best strategy to use on this stuff is to bring these problems up in class every time. If you teacher is making this stuff up, the need to be trained by their students to write better questions. If this stuff comes from a book or a test bank, it might get your teacher to do the stuff in advance and remove bad questions
2009-12-28 3:20 pm
Dividing by 1/2 is the same as multiplying by 2 so 70 is correct .There are 2 half's in 1
so ask yourself how many in 30 , remember when dividing by a fraction the fracion is inverted and
the operation becomes multiplication not division.
2009-12-28 3:45 pm
30 / (1/2) + 10

60 + 10

70
2009-12-28 3:23 pm
Dividing "by" half is not the same as dividing "in" half, at least for most of us.

Your interpretation would normally be stated as "divide 30 by 2".

I suspect this is a local language issue rather than a mathematics issue. You can see why it is important to be precise in terminology from this example.

The universal convention is that dividing "by" something means you use that number as the divisor, in this case 30/(1/2) = 60.
2009-12-28 3:22 pm
I don't know if someone has deliberately given you a trick question or not. "Divide by half" is strictly Divide by 0.5, which is multiply by 2. Many people sloppily say "divide by half" to mean divide by 2.

The correct answer is 70. If the original question was meant to be "divide by two" then the answer would be 25.
2009-12-28 3:18 pm
30 / 15 = 2
2 + 10 = 12
I say 12
2009-12-28 3:17 pm
It's 70.
Dividing by 1/2 would be the same thing as multiplying by 2.
2009-12-28 3:16 pm
30 ÷ 1/2 + 10
= 30 x 2 + 10
= 60 + 10
= 70
2009-12-28 3:17 pm
I agree with you i got 25 too.


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