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a) Divide 1 000 cm3 in the ratio of

      

a) Divide 1 000 cm3 in the ratio of $\frac{1}{4}$: $\frac{1}{2}$: $\frac{1}{5}$ leaving your answer nearest to 1 cm
b) In an experiment, a boy mixed some acid solution 45% concentration with an acid solution. In what portion should the two acids be mixed in order to get 100 cm3 of solution of 30% concentration?
c) Two blends of tea costing sh 140 and sh 160 per kilogram respectively are mixed in the proportion of 2:3 by mass. The mixture is sold at sh 240 per kilogram. Find the percentage gain

  

Answers


John
a) $\frac{1}{4}$: $\frac{1}{2}$: $\frac{1}{5}$ = 5: 10: 4

$\frac{1}{4}$ = $\frac{5}{19}$ x 1000

= 263. 16 cm3

$\frac{1}{5}$ = $\frac{4}{19}$ x 1 000

210.53 cm3

b) Let volume of 45% concentration be x 25% will be (100 - x)

0.45x + 0.25 (100 - x) = 30%

0.45x + 25 - 0.25x = 30

0.2x = 5; 2x = 50

x = 25 cm3

Hence volume of 45% = 25 cm3

Volume of 25%

= 75%

Ratio 25:75 = 1:3

c) 1 Kg of mixture cost

$\frac{140 + 2 + 160\times 3}{5}$ = $\frac{760}{5}$

$\frac{280\times 480\times }{5}$ = $\frac{760}{5}$

= sh 152

% gain is $\frac{240 - 152}{152}$ x 100

= $\frac{88}{152}$ x 100 = 57.9%
johnmulu answered the question on March 2, 2017 at 12:37


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