1 cubic meter of concrete has a weight of 2400 kg. 15% of the concrete is water. The rest of the ingredients are cerment, sand and stone. The weights are in a ratio of 1:2:5. Work out the weight of cement, sand and stone in the 1 cubic meter of concreteHelp me please i have a test coming up

Step-by-step explanation:

2400 × 0.15 = 360

2400 - 360 = 2040

2040 × 1/8 = 255 kg of Cement

2040 × 2/8 = 510 kg of Sand

2040 × 5/8 = 1275 kg of Stone

To check if it is right

255 + 510 + 1275 = 2040 kg

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

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