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There are n sweets in a bag, 6 of which are red. The rest of the sweets are blue. Jen removes 1 sweet from the bag. Jen then takes another sweet from the bag. The probability that Hannah takes two red sweets is 1/3. Show that n²-n-90=0.

We know the total number of sweets is n, and that 6 are red. When Jen takes the first sweet, the probability of it being red is [number of red sweets] / [how many there are] = 6/n . For the second sweet, ...

Answered by Amy B. • Maths tutor

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Lewis wins £360 in a prize draw. He gives 15% to charity and puts 3/8 into his savings. The rest he uses to buy a bike. How much of the money has Lewis got left for this bike? Note: do not use a calculator

10% of £360 is £36. Therefore 5% of £360 would be £18 (half of the 10% figure). Added together, 15% of £360 would be £54. 1/8 of £360 is £45 (half £360 three times), therefore 3/8 would be £135 (£45*3). £...

Answered by Lewis B. • Maths tutor

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Solve the simultaneous equations x^2 + y^2 = 9 and y = 3x + 3

y² = (3x + 3)² = 9x² + 18x + 9

x² + 9x² + 18x + 9 = 9

10x² + 18x = 0 (root a: x = 0)

5x + 9 = 0 (root b: x = -1.8)

Answered by Alistair R. • Maths tutor

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How would you increase 400 by 7%

First, we'd want to find out what 1% of 400 is. If 400 is the total number, that would make 400 the whole 100%. In order to find out 1% we'd want to divide the number by 100 which is 4. Now that we know 1...

Answered by Tharani T. • Maths tutor

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