數學 [20點]

1) In an online photo album, 40% are landscapes, 35% are portraits and the rest are 50 still image photos

(a) Find the percentage of still image photos in the gallery
(b) Find the total number of photos
(c) If 20% of the portraits are children's photo, find the number of children's photo

2) In July, the price of a stock increased by 10%. In August, it fell by 15%. Te closing price of the stock in August was $65.45. Find

(a) the closing price of the stock in July,
(b) the closing price of the stock in June,
(c) the percentage change in the price of the stock from the end of June to the end of August

3) By selling a wallet for $120, a retailer loses $30. Find the percentage loss.

4) A personal digital assistant (PDA) socting $3600 is sold at a 28% loss. Find the selling price.

5) A computer wholesaler sold a hard drive to a retailer at a profit of 5%. The retailer sold it to a customer for $1050, at a profit of 25%. Find

(a) the retailer's buying price of the hard drive,
(b) the wholesaler's cost price of the hard drive,
(c) the wholesaler's percentage profit if he had sold the hard drive for $1050 directly to the customer.

6) Find the discount percent of each of the following

(a) Marked price = $85, selling price = $51
(b) Selling price = $1216, discount = $384

7) In a Christmas sale, a down jacket is sold at a 20% discount. The selling price is $1480

(a) Find the marked price of the down jacket
(b) If the down jacket were sold at a 36% discount, what would be its selling price ?