CIE Mathematics Paper-1: Specimen Questions 69 - 71 of 175

Question number: 69

Short Answer Question▾

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Make y the subject of the formula: w=xyz.

Explanation

Here, formula is w=xyz.

So, w+z=xy

y=w+zx.

Question number: 70

Short Answer Question▾

Write in Short

y=p+qr

(a) Find the value of y when p=5,q=6andr=2 .

(b) Make r the subject of the formula.

Explanation

Here, equation is y=p+qr, where, p=5,q=6andr=2.

(a) y=p+qr=5+(6)(2)=5+12y=17.

(b) y=p+qryp=qrr=ypq.

Question number: 71

Short Answer Question▾

Write in Short

(a) The surface area of the earth is 510.1millionkilometers2 . Write this number to 3 significant digits.

(b) 72.2 % of the surface area of the earth is water. Calculate the area of water.

Explanation

Here,

(a) The surface area of the earth is 510.1millionkilometers2

  • So, correct it to 3 significant digits we will get: 510 because after 0 there is 1 which is less than 5, so 0 will remain same.

(b) 72.2 % of the surface area of the earth is water.

So, here surface area 100 %= 510 million

Then 72.2 %=?

72.2×510100=368.22millionkilometers2water

So, surface area of water on earth which is sphere = 4πr2=368.22r2=368.224×3.14=29.32r=5.41km .

So, for area of water on earth is: πr2=3.14×5.412=91.90millionkilometers2water.

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