
By: QiuJiao (offline) Sunday, July 25 2010 @ 09:41 PM CDT (Read 1906 times)



QiuJiao 
Dear helpers, kindly to help solve three promble sum, Thanks!
1) At present, Mary is 4 times as old as her sister. In 20 years' time, Mary's age will be 14 years less than twice her sister's age. How old is Mary now?
2) When Kok Hwa's age was twice Bala's age, Mike"s age was 30. When Mike's age was twice Kok Hwa's age, Bala's age was 21. Given that Mike was the oldest among the three persons, find Bala's age when Mike was 62 years old?
3) Mrs Hodge bought three times as many key chains as stuffed toys and spent $124 in total. She spent $64 more on the stuffed toys than the key chains. Given that a stuffed toy cost $8.40 morn than a key chain, find the cost of a key chain?

Newbie
Registered: 12/31/06 Posts: 8





By: suz855 (offline) Tuesday, July 27 2010 @ 02:13 AM CDT



suz855 
1) At present, Mary is 4 times as old as her sister. In 20 years' time, Mary's age will be 14 years less than twice her sister's age. How old is Mary now?
At present
Mary > 4u
sister > 1u
20yrs later
Mary > 2 parts 14
sister > 1 part
For age problem, concept >the difference remain unchanged
1 part = 20 + 1u, also 1 part  14 = 3u
replacing 1 part = 20 + 1u, we have 20+1u14 = 3u, > 2u = 6, 1u = 3
Mary (Now) > 4u therefore she is 12 yrs old
Checking, Mary is 12 and sister 3 (condition1 met)
20yrs later, Mary = 32, sister = 23
23 x 2 = 46, 46  32 = 14 (condition 2 met too)

Junior
Registered: 12/31/06 Posts: 16





By: QiuJiao (offline) Thursday, July 29 2010 @ 11:29 PM CDT



QiuJiao 

Newbie
Registered: 12/31/06 Posts: 8





By: lemofish (offline) Friday, July 30 2010 @ 03:32 AM CDT



lemofish 
see attached.

Newbie
Registered: 07/29/10 Posts: 9





By: QiuJiao (offline) Thursday, August 05 2010 @ 01:55 AM CDT



QiuJiao 

Newbie
Registered: 12/31/06 Posts: 8



