Let the total number of workers be x. 0.40(x) = Workers who have atleast 5 years of service(5 or more years of service) 16 workers have atleast 10 years of service (10 or more years of service) 0.90(x) = workers that have fewer than 10 years of service It then follows that 0.10(x) = 16 => x = 160 Wo...

Let x/y = 2/5.

(x + 4)/(2y) = 1/3 => 1/2(x/y) + 2/y = 1/3

1/5 + 2/y = 1/3 => 2/y = 2/15

y = 15

x = (2/5)(15) = 6

x + y = 21

Choose E.

Assume the car traveled x mpg on the highway and (x - 6) mpg in city. It then follows that:

462/x = 336/(x - 6) since both mileages (462 and 332) are on a tankful of gasoline.

336x = 462x - 2772 => -126x = -2772 => x = 22

So in the city, the car travels 22 - 6 = 16 mpg.

Choose B.

Average arithmetic cost of the x calculators = 300/x
Total amount received from selling all the calculator = (300/x + 5)(x - 2)= Total Revenue
From the problem:
(300/x + 5)(x - 2)= 300 + 120 = 420
300 - 600/x + 5x - 10 = 420
-600/x + 5x = 130
5x^2 - 130x - 600 = 0
x^2 - 26x - 120 = 0
x = 30
Choose E.

This question is unlikely on the GMAT but I'll definitely go ahead and take an attempt at it. This problem follows something known as the normal distribution and the 68-95-99.7 rule. This rule states that area under the curve 1 SD away covers 68% of the area, and similarly, area under the curve 2 SD...

Let x be the total amount of hospital expenses last year.
Amt. paid by insurance policy last year = 408 + 0.20(x) = 0.8(x)
408 = 0.6(x) => x = 408(5/3) = $680
Choose B.

Did you mean (4 - x)/(2 + x) = x ? If so, then:

(4 - x) = x(2 + x) => 4 - x = 2x + x^2 => x^2 + 3x - 4 = 0

Choose option 3.

5^(21) * 4^(11) = 2 x 10^n

5^(21) * 4^(11) = 2^(n + 1) x 5^n

2^(22) * 5^(21) = 2^(n + 1) x 5^n

Note that only n = 21 works in this case.