Math word problem help?

Confused: Math word problem help?
Soybean meal is 12% protein, cornmeal is 6% protein. How many Lbs. of each should be mixed together in order to get 240 lb mixture that is 9% protein?

Train A and train B travels in the same direction on parellel tracks. Train A travels at 80 mph, train B travels at 84 mph. Train A passes the station at 5:20am. If train B passes at the same station at 5:50am what time will it be when train B catches up to train A?

Answers and Views:

Answer by Chris P
00

Answer by jimbot
120 pounds of each (half and half since the 9% desired mixture is halfway between 6% and 12%)

When train B gets to the station at 5:50, train A is 1/2 hour * 80mph = 40 miles ahead.

Since train B travels 4 miles/hr faster than train A, it will take 10 hours to make up the 40 mile difference.

Answer by jic
1) 120lb of each.

(12/100 x 120) + (6/100 x 120) = 9/100 x 240 = 21.6lb

2) Train A is
= 80 x 1/2 hr
= 40m ahead of train B

Train B will take
= 40/(84-80)
=10h to catch up

5.50am + 10h = 3.50pm

It will be 3.50pm when train B catches up.

Answer by alejo
If 240 lb————–> 9%
then x—————> 6%

x = 6 x 240 / 9 = 160 lb

3%= 80 lb

then:

80 lb of Soybean and 160 lb of commeal.

———————————-
if 60 minutes—————————84m
in 1 minute———————————x

x = 84 /60 = 1.4 m per minute

the other one: 80 / 60 = 1.33 m per minute

1.33 x 30 = 39,9 m

39.9 / 1.4 = 28,07 minutes
then:
train A will be caught at about 6:18 a.m.

Answer by Jun Agruda
Soybean & cornmeal:
Lbs of soybean (x):
0.12x + 0.06(240 – x) = 0.09(240)
0.12x + 14.4 – 0.06x = 21.6
0.06x = 7.2
x = 120

Lbs of cornneak:
= 240 – 120
= 120

Answer: Soybean, 120 lbs; cornmeal, 120 lbs

Proof (9% protein in new mixture):
= 100%([0.12{120} + 0.06{120}]/240)
= 100%([14.4 + 7.2]/240)
= 100%(21.6/240)
= 100%(0.09)
= 9%

Trains:
No. of hrs train B catches up train A (x):
80(x + 1/2) = 84x
80x + 40 = 84x
4x = 40
x = 10

Time Train B catches up train A:
= 05:50 + 10
= 15:50
= 15:50 – 12:00
= 03:50 P.M.

Answer: At 03:50 PM that train B catches up train A.