Speed (S) = Distance (D) / time (t)
First stretch
45 = D / 2
D = 45*2
D = 90 mp
How is the same distance:
Second stretch
S = 90 / t
Average speed (AS):
AS = (S1+S2) / 2
60 = [45+(90/t)] / 2
120 = 45+90/t
120-45 = 90/t
75 = 90/t
t = 90/75
t = 1,2 h
________________________
And now:
S = 90 / t
S = 90 / 1,2
S = 75 mph
The cost of the mixture is $69 *$1 = $69. If all 69 pounds were peanuts, the cost would be 69*$0.99 = $68.31, which is $0.69 less. Each pound of walnuts used instead of peanuts adds $0.03 to the cost of the mixture, so there were $0.69/$0.03 = 23 pounds of walnuts.
<span>_____ </span>
<span>Let w represent the number of pounds of walnuts in the mixture. Then 69-w is the number of pounds of peanuts. The cost of the mixture will be </span>
<span>1.02w + 0.99(69-w) = 1.00*69 dollars </span>
<span>0.03w + 68.31 = 69.00 </span>
<span>w = (69.00 - 68.31)/0.03 = 0.69/0.03 = 23</span>
