Math QR word problems

[Jul18]

Ok, I might sound like the stupidest pre-dent ever. It had been a long day.

please help me with these questions...

1) A person in a motorboat traveled 48 miles upstream in 6 hours. The same trip downstream took 3 hours. find the rate of the current.

2) In a two-digit number, the ten's digit is 3 more than the unit's digit. If the digits are reversed, the new number is 27 less than the original number. Find the number.

a) 63
b) 74
c) 97
d) 52

I cancelled out C since the ten digit is not 3 more. but A & D both are rgiht though. Am I missing something? Thanks

3) An airplane took 20 hours to fly a distance of 1500 miles, flying against the wind. If the return trip took 12 hours flying with the wind, find the speed of the wind.

Mucha thanks.

---

Members don't see this ad.

 

[PooyaH]

Ok, I might sound like the stupidest pre-dent ever. It had been a long day.

please help me with these questions...

1) A person in a motorboat traveled 48 miles upstream in 6 hours. The same trip downstream took 3 hours. find the rate of the current.

2) In a two-digit number, the ten's digit is 3 more than the unit's digit. If the digits are reversed, the new number is 27 less than the original number. Find the number.

a) 63
b) 74
c) 97
d) 52

I cancelled out C since the ten digit is not 3 more. but A & D both are rgiht though. Am I missing something? Thanks

3) An airplane took 20 hours to fly a distance of 1500 miles, flying against the wind. If the return trip took 12 hours flying with the wind, find the speed of the wind.

Mucha thanks.

1. 48 miles x 6 hrs. = 288 m.hrs (distance)
288m.hrs / 3hr. = 96 m/hr

2. I guess there's something wrong with the question or maybe there's a fifth choice: e) A,B & D lol because all those reversed numbers will give 27 less than the original number!

3. I'd use the same strategy as #1:
1500 miles x 20 hrs = 30000 distance traveled
30000 / 12 hrs = 2500 miles
Now the speed of wind would be:
2500 - 1500 = 1000 miles

 

[Jul18]

Pooyah,

Those are not the answers for the 1st and 3rd. The answer for the first one is like 4mph... There's no explaination though.

 

[wasabi82]

Ok..
let x = speed of motorboat, y=current of the river.
then for upstream trip (x-y)6hr = 48 miles
and for return trip (x+y)3hr = 48 miles.
now you have two unknown and two equation. solve for y. it should come out 4.

for #3, it is basically the same question as #1.

I hope this is helpful.

 

[Andrew324]

Pooyah what are you even doing on that first one?

1) 48 miles upstream took 6 hours, 8mph
downstream 16 miles per hour
Difference 8, divide by two since well im not really good at explaining this part, current is working against the first one and with the second. I dont know someone else can better explain the divide by two. but
current = 4

Wasabi we posted same time your method is much more functional and can work in more situations, I like it!

 

[PooyaH]

Pooyah what are you even doing on that first one?

1) 48 miles upstream took 6 hours, 8mph
downstream 16 miles per hour
Difference 8, divide by two since well im not really good at explaining this part, current is working against the first one and with the second. I dont know someone else can better explain the divide by two. but
current = 4

Wasabi we posted same time your method is much more functional and can work in more situations, I like it!

Oh boy I totally misread the question! I didn't pay attention to the upstream and downstream. I totally misread it man. You're right...current would be 4!

 

[Jul18]

oh haha, can't believe myself... I should've trusted myself... Thanks guys!!!! you guys are so smart...