he human body is made up mostly of water. In fact, about 67% of a
person’s total body weight is water. If Jyoti weights 56 kg, how much
of her weight is water?
Rain forests are home to 90,000 of the 2,50,000 identified plant
species in the world. What per cent of the world’s identified plant
species are found in rain forests?
During school hours, Neha finished 73% of her homework and
Minakshi completed 5/8 of her homework. Who must finish a greater
per cent of homework?
A real estate agent receives Rs 50,000 as commission, which is 4%
of the selling price. At what price does the agent sell the property?
Sunscreens block harmful ultraviolet (UV) rays produced by the sun.
Each sunscreen has a Sun Protection Factor (SPF) that tells you
how many minutes you can stay in the sun before you receive one
minute of burning UV rays. For example, if you apply sunscreen
with SPF 15, you get 1 minute of UV rays for every 15 minutes you
stay in the sun.
1. A sunscreen with SPF 15 allows only 1/15 of the sun’s UV rays. What per cent of UV rays does the sunscreen abort?
2. Suppose a sunscreen allows 25% of the sun’s UV rays.
a. What fraction of UV rays does this sunscreen block? Give your answer in lowest terms.
b. Use your answer from Part (a) to calculate this sunscreen’s SPF.
Explain how you found your answer.
3. A label on a sunscreen with SPF 30 claims that the sunscreen blocks about 97% of harmful UV rays. Assuming the SPF factor is accurate,
is this claim true? Explain
For an amount, explain why, a 20% increase followed by a 20%
decrease is less than the original amount
Living on your own: Sanjay is looking for one-bedroom appartment
on rent. At Neelgiri appartments, rent for the first two months is
20% off. The one bedroom rate at Neelgiri is Rs 6,000 per month. At
Savana appartments, the first month is 50% off. The one bedroom
rate at Savana appartments is Rs 7000 per month. Which appartment
will be cheaper for the first two months? By how much?
A store is having a 25% discount sale. Sheela has a Rs 50 gift voucher
and wants to use it to buy a board game marked for Rs 320. She is
not sure how to calculate the concession she will get. The sales clerk
has suggested two ways to calculate the amount payable.
– Method 1: Subtract Rs 50 from the price and take 25% off the
resulting price.
– Method 2: Take 25% off the original price and then subtract Rs 50.
a. Do you think both the methods will give the same result? If not,
predict which method will be beneficial for her.
b. For each method, calculate the amount Sheela would have to pay.
Show your work.
c. Which method do you think stores actually use? Why?
At a toy shop price of all the toys is reduced to 66% of the original
price.
(a) What is the sale price of a toy that originally costs Rs 90?
(b) How much money would you save on a toy costing Rs 90?
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