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17 votes
17 votes
Which two of these fractions are equivalent to 1/4

A. 3/15
B. 2/8
C. 5/20
D. 11/40​

User Gregor Ophey
by
2.9k points

2 Answers

29 votes
29 votes

Answer:

B and C

Explanation:

To find out if fractions A/B and C/D are equal, we can do either of 2 things:

1. Reduce them both to simple form (a form where the greatest common divisor "GCD" of numerator and denominator is 1 and the denominator is a positive integer)

2. Check if A*D = B*C, because if A/B = C/D, then we can multiply both sides by B*D, getting

A/B*B*D = C/D*B*D

A*D = C*B

We'll do the former for A and B and the latter for C and D.

Firstly, 1/4 is irreducible, because GCD of 1 and another number must be 1.

A. 3/15 = 3/(3*5) = 1/5

not equal to 1/4

B. 2/8 = 2/(2*4) = 1/4

equal to 1/4

C.

1*20=4*5

20=20

true, so 5/20 = 1/4

D.

1*40 = 11*4

40 = 44

false, so 11/40 does not equal 1/4

User Konvas
by
2.9k points
23 votes
23 votes

Answer:

B and C are correct

Explanation:

2/8, because 2/2 is 1, 8/2 is 4, so it is equivalent to 1/4.

5/20 because 5/5 is 1, 20/5 is 4, so it is also equivalent to 1/4.

User Jafar Isbarov
by
2.6k points