## Math Brain Teaser- Erin’s Grandma

Currently, Erin’s age plus her grandma’s age equals 94. In 4 years, Erin’s grandma will be 5 times as old as Erin. How old is Erin currently?

*This can be solved without any formal algebra training. Answers can be submitted below, will reveal before the week is over!*

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Hendy| Profile June 22nd, 2010 - 2:17 amGrandma is 81 and Erin is 13.

81 + 4 = 85.

13 + 4 = 17.

17 * 5 = 85.

cheddarmelt| Profile June 22nd, 2010 - 5:08 amIn four years their total age should increase by 8 (four for each), totaling 102. Divide that by six (one for Erin, five for Grandma), and you get 17. That’s Erin’s age in 4 years. So she’s 13 now. (Grandma is 81.)

hakoly1018| Profile June 22nd, 2010 - 7:27 am13 years old.

Shawn| PUZZLE GRANDMASTER | Profile June 22nd, 2010 - 7:55 amErin is 13

BlindCupid| Profile June 22nd, 2010 - 8:07 am15 2/3

engjs1960| Profile June 22nd, 2010 - 8:52 amErin is 13.

mimi112| Profile June 22nd, 2010 - 11:22 amCurrently Erin is 13 years old and her grandma is 81. In 4 years, Erin will be 17,and grandma 85 wich is 17*5.

suineg| PUZZLE MASTER | Profile June 22nd, 2010 - 12:10 pmI think the answer is 12 years and 4 months

Explanation: G: Grandma age, E: Eric age

Time = 0 –> E+G = 94

Time = 4 –> E + 5E = 98 ( G = 5E 4 years later)

6E= 98 E= 16.33… years –> 16 years and 4 months, but that is in time= 4

so in Time= 0 E = 16.33- 4= 12.33–> 12 years and 4 months

Falwan| Profile June 23rd, 2010 - 1:18 am81;13

Falwan| Profile June 23rd, 2010 - 1:18 am81;13

With equations!

virgolady85| Profile June 23rd, 2010 - 3:19 amE+G=94

but G+4=(E+4)X5

G+4=5E+20

G=5E+16

so E+(5E+16)=94

6E=78

E=13

Erin is 13 years old.

Bobo The Bear| PUZZLE MASTER | Profile June 23rd, 2010 - 5:32 pm>”This can be solved without any formal algebra training.”

I’ll take a stab at the “non-algebra” solution, for a change.

The combined age now is 94. In 4 yrs, add 4 to each age, making the combined age 94+4+4=102. The ratio of these ages is 5 to 1, or five parts Grandma to one part Erin, for a combined six parts. 102 broken into six parts makes each part 17. In 4 yrs, Erin will be 17 and grandma will be 17*5=85. So now Erin is 13 and grandma is 81. And 13+81=94.

Hex| PUZZLE MASTER | Profile June 24th, 2010 - 4:09 amErin is 13 years old

atulatul| Profile June 25th, 2010 - 4:47 amErin is 17 yrs old currently

Sarah Al Taher| Profile June 28th, 2010 - 6:07 pmlet x be the current age of Erin

y be the age of her gran…

x+y=94…(1)

5(x+4)=y+4>>> 5x+20=y+4>>>5x-y=-16…(2)

add (1) & (2) to have:

6x=78>>>x=78/6=13 >>>y=94-13=81

Erin 13

gra…81 ))